10 things perpetual third wheels want all couples to know.

We bet Harry is so done with Kate and Wills’ in-jokes. (Image: Getty)

To have a good friend, you need to be a good friend, as the saying goes. This might require you to hold back your mate’s hair while they throw up the contents of their tequila-riddled stomach, or to pick them up from the airport at 10:43pm because they don’t have enough cash to buy dinner let alone a taxi ride.

But you’ll happily do either of these things ad infinitum if it would grant you immunity from the role of Perpetual Third Wheel.

Don’t get us wrong — of course you’re going to be happy when your best mate finds a mate of their own. And when you enjoy his or her company too, you don’t mind hanging out as a mini gang. But when you’re playing accessory to the fact for the fifteenth weekend in a row, things start to grate.

Here are 10 issues the perpetual third wheels (or worse — fifth, seventh, ninth wheels) wish to raise with their coupled-up friends.

1. Your “sneaky” kisses aren’t sneaky. At all.

You think you’re so sly, huh? Maybe it’s the sly side-pash in the cinema when we’re sitting right next to you. Maybe it’s the opportunistic peck when we’ve stopped to tie up our laces. Whatever your trick happens to be, you’re not getting away with it.

We third wheels see everything, because we’re usually less than a metre or two away from you. And if we don’t see it, we hear it. Yep, your lip smacking and slurping is audible over even the wildest action film soundtrack.

2. Do you really have to do everything together?

Certainly, life is grand when you find 'your person'. But as your friend, we remember life before you met that person, and we know you functioned perfectly well on your own.

So why does your love friend have to come to every single coffee date with us? Do they carry life-saving medication? Do you share vital organs now? As much as we might like them, we don't always want to discuss our most recent pap smear without your partner listening in.

Watch: Aussie celebrities share their "Hall Passes". (Post continues after video.)

3. We feel awkward when you argue in front of us.

It doesn't matter if you're yelling at one another in the street or slinging passive-aggressive barbs across your smashed avo at brunch — we didn't sign up to bear witness to your romantic bugbears. And stop trying to make us take sides (although, just quietly, we totally agree that Tom should take the bins out without you having to ask him five times.)

4. For the love of Ryan Gosling, quit the in-jokes. Please.

"Remember that time when..." No, we don't remember, because we weren't there. Nor do we understand why the word "pineapple" makes the two of you erupt into uncontrollable giggles (hence the blank look on our face). We don't expect you to explain every single intimate joke you have, but maybe try not to completely isolate us.

5. We need to talk about baby talk.

Specifically, why it needs to not happen. We're all grown adults here. Let's just remember that.

6. Pet names, too.

Unless they're a joke, please drop the "Baby"s or "Sexy"s or "Schnookum"s or anything of this description in our company. It feels way, way too intimate. (Post continues after gallery.)

7. When it comes to Netflix and chill, three's a crowd.

Movie nights on the couch are the best... until you start snuggling up right next to us. The movie isn't that scary, guys. And there's plenty of room for three people to sit comfortably without overlap. Honestly, if you're in the mood for a romantic night in feel free to just not invite us. We won't take it personally.

8. The footpath issue.

Unless you're strolling in a spacious country town, footpaths aren't always wide enough to accommodate walking three abreast. Obviously, one person is required to drop back in these situations — and by default, it's going to be the third wheel.

This isn't the path to Noah's Ark, guys. You won't be separated if one of you takes the hit once in awhile. Same goes in booth-style restaurants. Let's share the love.

9. We don't need to be reminded that we're third-wheelin'.

Everyone knows what's going on here — we don't need you to blatantly acknowledge that we're the third wheel. Until you mentioned it, we were fine thinking we were just hanging out with friends.

10. Stop treating us as your "project".

If we happen to be single, trust us: we are aware of the fact, and we (probably) don't need or want you to play Cupid. We're sure "Alex from the IT department at Sam's work" would be a great blind date, but unless we've asked for your help just leave us in peace. Just because you've found love, doesn't mean you have to turn your attention to "saving" us.

Are you a perpetual third wheel? How do you feel about it?