A release of endorphins in the brain which causes weakness of knees and sexual tension in females and a desire of emulation in males. It is brought on by the presence of, thought of, or mention of The Dave.
As Gary mentioned Dave, Daniella felt her knees go weak and knew she was experiencing the Dave Effect.
The phenomenon that causes females to be repulsed by the mention of Dave. It is believed to be triggered by Dave's chronic knowitallism and overall weirdness. Other possible causes include a funny smell, a funny face, and a geeky demeanor.
"Hey Sarah, do you know Dave?"
"Ew, don't even say that name. It gives me the heebee jeebees."