look up any word, like dirty sanchez:
 
15.
SPD
That's SBD not SPD....
That one was Silent But Deadly.
by Anka August 23, 2004
 
16.
SPD
Is and abbreviation for silent but deadly which usaully relates to a silent expulshin of methane gases and has terrible oder and hang time
Ohh what smells i didnt even here it comming
by Jack Meoff May 05, 2004