When the person on the performing end of fellatio quickly and thoroughly spits out the other's love juice, resembling a sprinkler system. This is usually in response to a "surprise" attack, but not always.
Don't even think about asking Shaniqua for a blowjob, she'll go all rainbird on you. Instead, dangle that cock-sicle in Kimberly's face. She'll lap it all up.
"Man, I saw Rainbird at the Espy
last night! They were iNsAnE!"
someone from the "rainy states" (oregon/washington)
Seattle is full of rain birds.
To cum so forcefully that you go off like a lawn sprinkler
I caught Scott on a porn site last night, he was going rainbird on his desk!!