suuuuuuuuuuuuup

the trick is to remove anything that makes the greeting actually cohesive
you can utter absolute gibberish as long as it flows well and is short and snappy

buyakasha!

or you can throw in some insults to throw off the person even more

hey fuckface!

Whatever you say it cant be logical or straightforward because the person subconscious wants to either answer properly or one up you.

schoobity doobap!