The valve(s) found on a brass-wind instrument that are opened to release saliva accumulated while playing.
You're rattling. Empty your spit valve.
by Chad June 20, 2004
when an unusually tall girl is giving a man a rusty trombone in the 69 position while pissing in his mouth
"That Josh Watson is a lucky man dating that ckick basketball player, she's so tall that she spit valved him last night."
by H2zZ December 09, 2004