Head over heels. Used frequently by weird Canadian mother-in-laws.

to fall over badly

to fall in such a way that you flip over, ass over head or head over heels

When one is hit by something stopping their front side but the rear continues going up and forward causing a roll

When a woman is so easy that a perfect stranger can go up to her and ask her if she wants to fuck and she says yes.

Being dumb, stupid, confused, perplexed,

to fall in such a way as your bum flips over your head