Every sport has its fundamental rules that are pretty to learn, understand, remember and stick to so it's absolutely hilarious when the professionals manage to completely mess up by forgetting them.
Sport isn't always to understand. Sure most of us get the offside rule but every now and again it gets slightly changed and everyone loses their shit and it takes three years for us to understand it again.
Cricket isn't easy to explain to people and there's the famous explanation to a foreigner about the men who are in going out until they're out and then they go in.
See even he doesn't know what's going on in the scrum. Image: PA Images
Even rugby fans spend half of their time trying to work out why a penalty was given in the game and they can't begin to explain half the decisions to a non rugby fan.
However one rugby rule that is pretty simple to understand is that you can't pass the ball forward, let go of the ball and it's got to go behind you or to the side. Everyone knows that, right?
Well one Samoan rugby 7s player managed to forget that in the London 7s at the worst moment, when he'd already gone past the try line:
It's almost like the passer completely forgets which way round forward and backwards are just because he's turned round to see where his teammate is.
The waiting for him as well, it's all so painful. The receiver maybe should have stopped and realised what his colleague was waiting for but seriously why is anyone throwing that pass.
The moment of madness happened after just three minutes of their game in the group stages against Spain and it might have cost them.
Fortunately Samoa went on to win 26-10 but it was Fiji who won the tournament, knocking up their fourth win in a row.
If you're going to play rugby professionally you should probably know the rules.