Priorities, your sister has them.

So she wants to have her cake and eat it too.

Should've threw that piece of cake in your sisters face

*thrown

Also, no. That's a waste of precious cake.

You took the first piece of cake of someone else's birthday cake?!?!

Is that actually a thing that matters for some people? I don't think i've ever cared or even noticed what order my slice of Birthday cake was cut in. I'm usually just hoping my nephew didn't spit all over it when he helped me blow out the candles.

It's just usually a tradition that the birthday persons cuts the cake and has the first slice. Definitely not a big enough offense to break up a relationship, but annoying nevertheless.

I would have flipped my lid as well. It's the one day my 5 friends I have left post HBD on my Facebook lol

I personally probably wouldn't care but unless she hands it to you that was a total dick move so I really can't feel bad for OP. The birthday cake belongs to the birthday person and they share it with you.

Have to agree, big dick move op. Not enough to warrant what she did, of course, but still pretty selfish.

#4 Definitely not okay, but the punishment didn't fit the crime.

Eh? Usually, where I live, the birthday person cuts the cake and hands it out to everyone so the birthday person gets the last slice

Same here... In our family, and at every Birthday party i've been to the birthday boy/girl cuts the cake (sometimes with parental help) and then passes it round, except me because nobody really trusts me with knives. Severed fingers tend to ruin Birthday cake. But either way, cake is cake, it's gonna taste the same no matter when it was cut so it seems awfully petty to even care who gets the first slice, let alone seek retribution because it wasn't you.

the first piece isn't that big a deal honestly, but then again in my family it usually goes like this: everybody else gets some (equaling about half a cake) and the rest is the solely the birthday person's to enjoy for a couple days and only shares if they want to.

Either your girlfriend is very gullible, or your sister should consider becoming a lawyer if she's not already.

It's easy to break people up. It's all about planting that seed of doubt. And having answers for questions that are plausible on their own. Slip'em the hook with the little lie, and you'd be amazed what kind of whoppers people will swallow.

"He said he was at the mall, but I swear I heard a car horn. He must have lied." That kinda circumstancial shit adds up. When in actual fact he was probably walking through the mall parking lot to get into the mall. Or walking past one of those coin-op car rides.

Cheating is also a pretty easy thing to convince people of, as it becomes extremely "he said, she said." OP's sister only needs to say that she saw OP cheating at some time when OP had actually been hanging out alone. Naturally OP will deny it, but what cheater doesn't deny cheating? Unless OP is constantly surrounded by people who can vouch for him, he's got no real proof he didn't cheat. And if the gf asked why OP's sister made it all up, the reason "I ate the first piece of her cake." sounds like a pretty lame excuse.

Your sister is a bitch, your girlfriend is stupid and you're an asshole.

Never take the first slice unless it's your birthday. Still your sister was wrong

She was wrong by being too merciful.

Tbh, I probably would have done the same thing. YDI for taking the first slice of someone else's BIRTHDAY cake

Yes because that clearly warrants the sister to break up a relationship.

It's not like Op destroyed the whole cake or ate it before anyone else got a chance. Yes, it's nice to let the birthday person eat first, but damn... breaking up a relationship over cake is crazy.

"Today, my brother ate the first slice of MY birthday cake. FML........ But don't worry. I'm already plotting revenge. "

"Today, I found out my boyfriend cheated on me. I wish his sister had told me before I gave her the expensive present I got her. FML."

As much as that is God awful you probably should have had an idea of what your sister is capable of. Assume that no matter how trivial she will do her worse.