Basically anything. Essentially it can be used as any noun or a verb in the past tense. Though it isn't a good idea to use it as a gerund.
Noun usage: Yo, I was chatting with Doug the other day and he picked up that falala and wants us to come over and check it out before we take off.
Verb usage: Sarah was so pissed that Jerry put his nose in her mouth, she falala'd his ass all night.
Falala is an expression you can use when you have nothing to say or cant think of anything nice to tell anyone.
When your in an argument and cant defend yourself, or cant back up your argument yell
FALALA give a real mean stare down and walk away as easy as that.