A sister-in-law, they’ve married your brother or sister and tethered themselves to your family. 

Tightly and unyielding, like a pair of sloth hands clamped firmly upon a dry old tree branch. Their little cute grins and fuzzy eyes masking the horrors that lurk beneath. 

Then before you know it, you wake up to find you’ve all been killed in your sleep and the family safe has been emptied.

Or we could be less dramatic and consider the fact that your sister-in-law might be an absolute delight. 

Whichever kind of in-law you get, their birthday is an inevitability. 

So, if you’re wondering what to write in a birthday card for a sister-in-law (whether they’re evil or completely unproblematic) we have you covered with our list of funny birthday wishes and naff poetry.

Let us dive in. *insert massive splash sound effect here*

• To my sister-in-law, I was going to put money in this but there’s no amount high enough to make living with my brother even slightly bearable. 
• Happy birthday to my sister-in-law. I was trying to think of a joke but then I remembered you live with my brother. 
• Happy birthday sister-in-law. You’re more than good enough for my brother. I mean just look at him.
• You’re a bit like my brother, I didn’t ask for you, I didn’t like you at first, you get on my nerves but I’m so glad you’re here. 
• Happy Birthday to my sister-in-law. Here’s to bitching about my brother.
• Happy birthday sister-in-law, funny thing to do marrying my brother wasn’t it? Are you sure you’re well?
• Happy birthday to my amazing sister-in-law. While you’re there tell my brother to give you a tenner, I’m not made of money. 

• I smile because you’re my sister-in-law, I laugh because you have to put up with my brother.
• Happy birthday sister-in-law, you’re the bravest person I know… for putting up with my brother day in and day out. 
• Happy birthday sister-in-law. Hope that massive pain in the arse isn’t giving you too much grief.  
• Not really sure what drugs you were on when you decided to marry my brother but I’m so glad you did. 
• I couldn’t think of any funny sister-in-law quotes so I’ve just said, ‘live, laugh, love’. Although in your case it’s more ‘hate, cry, die’. (I’m so sorry you’re lumbered with my brother).
• Happy Birthday sister-in-law, I know what my brother’s got you. Don’t get your hopes up. 
• Happy Birthday to my sister-in-law. Congratulations on surviving another year with my brother.
• Happy birthday to a unique sister-in-law. It takes a special kind of stupid to take a look at my brother and think ‘I’ll marry that’.
• Happy birthday to a fantastic sister-in-law. I’m so glad he’s your problem now.

• A beautiful, headstrong, talented, tenacious woman… is wishing their sister-in-law a happy birthday with this card.
• What can I say about having a sister-in-law that isn’t going to offend you on your birthday?
• Have a great birthday sister-in-law. How’s your back from carrying the whole marriage for yet another year?
• Happy Birthday, time for me to boot lick for the day and pretend I like you.
• Happy birthday to the secretly evil sister-in-law. Or maybe I’m the evil one?
• I wish everyone had a sister-in-law like you. It’s not fair that it’s only me who has to put up with it.
• I can’t believe you actually volunteered to be part of our family. Why not volunteer for something less complicated, like the army or kidney donation?
• Happy birthday sister-in-law to the only woman mad enough to want to spend the rest of their life tethered to this family.
• Happy birthday to my sister-in-law. I was going to put money in this but then I remembered I don’t actually like you. 

Of course, if possible, you can also make stickers of what you want to say to your sister-in-law and post them on the wine bottles or cup at the party, which can be used to express birthday wishes to her or express your hard work to her with simple quotations. Of course, it also can be a joke to liven up the atmosphere. You can tell the sticker designer what you want to say to your sister-in-law, and they will make what you want. Come to BPS !

• A sister-in-law is a bit like a vaccine, I never asked for it, I didn’t really want it, and you were an absolute pain to start off with but I suppose you came in useful in the end.
• This card is to the most amazing sister-in-law in the world. I didn’t know her address though so I sent it to you. 
• Happy birthday sister-in-law. You deserve a day off, you look rough.
• To my sister-in-law on her birthday, l suppose you’ll do.
• What’s the best thing about a sister-in-law? Nothing. 
• From now on I’m calling you my sister-in-lore so it sounds like we have some mad mythical history going on.
• Happy Birthday Sister-in-law. You’re the Meghan to my Kate. Take that however you want.
• Happy birthday sister-in-law. I’m glad your family is just as crazy as mine.
• Happy birthday sis-in-law. My only sensible sibling. 
• I don’t know whether you’re brave or a complete fool for voluntarily entering into this family.
• I couldn’t have asked for a better sister-in-law. But then again, my bar was set really low.
• Happy birthday to a sister-in-law who is just as mad as me.
• You’re a bad mannered lush with the foul mouth of a sailor. That’s all I ever wanted in a sister-in-law.
• Happy birthday to my haggard old bag of a sister-in-law.
• Happy birthday sister-in-law, you don’t half look your age.
• Happy birthday to a wonderful sister-in-law. I’m so glad your parents kept you.
• To my wonderful sister-in-law. You’re a lot nicer than I thought you were going to be.
• Happy Birthday to my sister-in-law, a woman lucky enough to have avoided my family’s dodgy genetics.
• I bet you didn’t think it was going to be this chaotic marrying into our family.
• To an amazing sister-in-law. Yes, it’s too late to run.

Happy Birthday sister-in-law, to this day I’ll never understand,

What made you say I do when asked to take my brothers hand,

Listen very carefully, I’ll warn you only once,

The man that you are married to is a complete and utter dunce.

Happy Birthday Sis-in-law, I’m so glad you’re in this fam,

My family are weirdos but you don’t seem to give a damn.

I’m grateful for this fact but if you ever need reprieve,

Do not worry sis-in-law, it’s not too late to leave.

Happy Birthday Sister-in-law, you’re the only one up to the job,

To be my brand-new sister, even though I’m an utter knob.

I may be an annoying step bro, but there’s no one else I’d rather see,

Welcomed into our family as a new place in the family tree.

Promotion Image

Brother marries a fool,

Fool makes tit of herself,

It’s you.

Summary:

Well, there we go, that was a fun trip into my mind wasn’t it? 

It’s usually just white noise in there and the occasional existential scream when my brain decides to fire some neurons to my mouth. 

But alas, we have gotten to the end of this article and I hope I have sparked your creative juices as to what funny messages to write inside a birthday card for a sister-in-law.

And if not, just leave a penny in my hat on your way out. 

While you’re here however, why not browse some of our funny birthday cards for her or check out some funny sister quotes (if you have one that is). 

We have a very wide range available and you’re sure to find something you’ll love. 

Give them a cheeky look and thanks very much for stopping by.