Young Thug & 21 Savage Make it Rain in Atlanta Club

Young Thug and 21 Savage can't help themselves -- when beauties come twerking so does a bunch of cash!!

The rappers attended something called The Ultimate Twerk Off at Club Crucial in ATL ... where a bunch of chicks went hard in front of the rappers, and that prompted a bag of cash to make an appearance.

Check it out ... YT and 21 also spread the wealth to a bunch of clubgoers ... which for some odd reason were treated to what looks like an amateur boxing match.

All in all, Young Thug tossed around $20k and Savage unloaded $10k.