Kevin Hart Mostly Fails at Dunking Off a Trampoline

Here's the latest edition of "Kevin Hart vs. Height" ... where the actor/comedian tries to slam dunk using a trampoline as his launchpad -- and it's a struggle.

Kevin's attempted dunk sesh went down at one of the Sky Zones around L.A. over the weekend ... where it looks like the Hart fam was out celebrating the 13th birthday of his daughter, Heaven.

The NBA super-fan didn't want the kiddos to have all the fun, so Hart stepped up to the glow-in-the-dark Sky Slam ... and repeatedly got knocked on his ass while his wife, Eniko, yucked it up.

But, Kev didn't let the verticality shaming get him down ... and eventually got up for a 2-handed jam!!