>>126959754 (OP)If you're talking, genuine, not scripted/prepared verse freestyling:
Lupe once said...
you need to unironically read a LOT of stuff. Like books, dictionnaries. Like an unironic autist, obsessed with words. Then once you find words that sound funny to you, you try to pair them up with other words that sound, look or spell almost the same. And then you repeat with the next word.
By now, you managed to make a simple, improvised freestyle.