They belong to you both- These jokes are something that are yours- together- no one else understands why they're so funny but that's ok because it's your little secret.

It's important to make each other laugh- In-jokes are a guaranteed way to get your partner smiling and vice versa.

They can bring one or both of you out of slump- If one or both of you has had a really bad day, a few words will cheer them up and make them forget all about it- just as some choice words from them will do for you.

You can relive a moment in your history- If the in-joke comes with a story- chances are you will go over old ground and think about some of the great times you've had together.

There's no judgement- You have your own little sense of humour together so if the in-joke is a little off beat- they won't be fazed by it and be thankful that someone else is on their wavelength.

It brings out your childish side- When you're both working, have bills to pay and responsibilities- it can make a refreshing change to laugh like you're a kid again.

They can get you through hard times- If you're going through a difficult time together, remembering the more lightheaded moments in your relationship can give you faith that you'll have them again- just once you get over this bump.

It reminds you both you have the same sense of humour- Your friends and family might not get on board with your way of thinking- but the most important thing is that you get each other and regular reminders of this can only be a good thing.