If you've ever been obviously checking out a guy and then your friend decides to "claim" him by walking up to him and touching his polo shirt and exclaiming, "I'm soooo drunk right now omg!"- you've been clam jammed.
If you've ever been hitting it off with a guy and then you tell him his pong game is weak, you've been clam jammed.. by yourself, I might add.
Friend: I am Sexy Bexy and this is my friend Steephy Queefy.
Boy: *walks away*
Queefy Steephy: You Clam Jam me every time with that nick name!