Not with any normal swing.
Swings normally use chains or ropes to hold the seat. Since these are flexible, whenever you swing past 90 degrees (straight out from the top bar) the chains will go slack momentarily as you drop back down. The higher you manage to swing, the worse the drop gets. This prevents you from building up more momentum that would be needed to take you over the top.
To go over the top, you either need to: 1. replace the chains with rigid bars so you can keep building momentum past the 90 deg position with each swing. Or 2. you need something that can give you a really big push to get you from the 90 deg. to over the top in one push (elimination any need to slowly build momentum).
I'm almost positive that happens only in cartoons...
I don't think so. I almost did it one time though. I almost flipped over the entire swing-set.
Lol! Wow........... Ouch.....