When your girlfriend isn't around, so you decide to have sex with a turtle.
"Did you hear about Dave? He went Shell Knocking since Cathy's out of town!"
When a female has a block of cheese in their vagina
I gave my girl a stuffed shell. We had to go American because sharp leaves a bad taste in my mouth.
When you get a triple green shell or red shell in Mario Kart and keep it as a shield to avoid other shells. Unfortunately, shell shields are busted by the 'naners.
Shells are used to smack people around.
I pulled out a shell shield. Wario, Ludwig, and Rosalina all went down. Then I just sped ahead to first.
The most selfish person around. He hides when he's getting attacked and attacks other people for fun. Hence the term half shell.
Man, Cody is such a half shelled bitch. He told that depressed kid to die and when he got all the hate he played victim.
When a cold gust of wind hits a man and his penis retreats back into its body, such as a turtle when it gets scared.
“So did you go all the way with Sally?”
“Nah I got shell shocked before I walked in”.
A medical procedure during which you put on a 15 lb lead cannonball shape module around your testicles to protect them from irradiation. While the procedure is quite cold and difficult to not pinch yourself, it is not that hard as long as you are not attempting to put your penis inside the module.
Patient: "Gahhhhhhhhhh. Phew, Nurse I swear to god this is so difficult, but I have finally completed the Clam Shelling!"
Nurse: “You...uh - you don’t …. uh … You don’t actually have to put your penis in it?”