This is combination of two words. Freak and Flip. This is used best when someone has a violent reaction to something suprising or irritating.
Kyle fleaped out when he pulled a spider out from underneath the cabinet. "Hey Kyle, calm down, it's only a spinder. No need to fleap!"
To fleap (past tense, flept) is to perfrom an intricate act comprising simultaneously flipping and leaping, in that order. Note that leaping, and then flipping does not count; first you must flip, then you must leap. Originally used in the circus community (e.g., the popular Fabulous Fleaping Five), it may now be used colloquially to describe any sort of exuberant outburst.
"Wow, did you see Andrew when the vending machine gave him an extra dollar in change?"
"Yeah, he was positively fleaping with joy."
A combination of the words fuckloads and heaps when neither of the two words can sum up just how much of a quantity there was.
Can also be used in the variant fleaping.
1) "How many people were at the gig last night? I heard it was crowded."
"Fleaps man, fleaps."
2) She said she was into thrupping
. Isn't that fleaping disgusting?