Don't do it, under any circumstances!

Alternative form of black don't crack

A slogan of the hippy movement, dismissing perceived prudish and conservative attitudes of previous generations.

Black people and white people should not form relationships; an admonition against miscegenation. / (more generally) Some people, things or characteristics do not go together.

(humorous) Don't make long-term plans, as you may not live/survive long enough to accomplish them.

Indicates that the speaker does not eat beef.

Used to clarify that something previously said did not have a meaning that could be misinterpreted.

(informal, idiomatic) Indicating that one is serious and not joking about a matter.

(idiomatic, US, informal) Barring unforeseen circumstances.

(US, dated) Do not permit yourself to be cheated or duped; do not be naive.