1. pulling back on the hammer of a revolver pistol to be in ready position to strike the percussion cap/primer, to ignite the propellant and fire the bullet.
2. pulling back on the skin of the penis shaft near climax for a more effective ejaculation
to ingest Yohimbe or viagra or any erectile stimulant before sex in order to make the penis harder then it naturally is. Intercourse performed during hammer cock sessions should be very rough and performed almost in it's entirety in standing up doggie style. The complete act is referred to as hammer cock, or hammer time for short.
"Have you ever had hammercock"? "yo, last night, I gave that chick hammer cock"!
When your cock is limp and even a hammer couldn't get you hard.
Four blows from Granny's rusty, cast-iron mallet could not awaken Bapa's hammer cock from its deep, alcoholic slumber in the dusty chambers of his cordoroy pants.