[riverrunner]

The masked robber jumped the unarmed security guard about 2:15 p.m. inside the QVL Pharmacy at 850 FM 1960 near the North Freeway

Unarmed security is about as useful as tits on a boar.

[T-Bird45]

Unarmed security is about as useful as tits on a boar.

An excellent simile. I wonder if the retired trooper will now re-evaluate the usefulness of unarmed security at his employer's drug stores.

[T-Bird45]

Unarmed security is about as useful as tits on a boar.

I also like to go for the twofer and use alliteration along with the simile: "as worthless as tits on a tomcat".