Aly Raisman's Dad -- Hassled By Grumpy A-Hole During Olympic Gym Finals

Aly Raisman's father stood up and cheered his face off after his daughter pulled off the greatest performance of her life last night ... which REALLY pissed off the cranky bastard who sat behind him.

It was HILARIOUS ... with his daughter about to receive the gold medal for the individual floor routine, some Olympic party-pooper grumpily reached over to Rick Raisman ... and nagged him to sit down and shut up.

Of course, Rick totally ignored the guy ... and probably cheered even louder.

So sorry America ruined your evening ... you black hole of fun, enemy of awesome, enjoyment-sucking pain in the ass.