What does "built like a brick outhouse" mean — and why is it funny?

informal, humorous

Meaning

Describes a person, usually a man, who is very large, solid, and powerfully built.

Where it comes from

A folksy American and British phrase. An outhouse — an outdoor toilet — was usually a flimsy wooden shed, so one built of brick was absurdly, needlessly sturdy.

Why it is funny

The humor is the choice of building. To praise someone's impressive frame, the phrase compares them not to a fortress or a tank but to an unusually well-made outdoor toilet.

Used in a sentence

"The new bouncer is built like a brick outhouse."