Phrase. Means to drop soap as stated. Famous in prison movies when a man is taking a shower and drops his soap, leading him to gettin analy raped. Also mentioned in cartoon the Boondocks. There is a phrase related, "drop soap" which means to screw up and to recieve grave consenquences.
1. A remark made to someone being hauled off to jail, particularly someone you dislike. Once in jail, you imply that if the person (a male) drops a bar of soap in the shower, they will be forced to bend over and retrieve it. Thus, with there buttocks spread and in clear sight, will be subject to anal rape by a fellow inmate.
"Don't drop the soap!" I yelled as the burglar was taken away by the police from my home. His eyes began to tear up as he anticipated that hot, steamy shower.
To "Drop the soap" is to accidently, or absent mindedly, put yourself in a vulnerable position. Derived from the idea that in a prison shower, if you were to drop the soap, and bend over to pick it up, you would expose your anus to rape.
"We're surrounded, don't make any sudden moves, and for christ's sake don't drop the soap!"