did not (negative auxiliary)

Negative of used to

(Internet, humorous) Unless one can provide the proof that one is requesting, that person has no credibility in the matter.

Alternative form of pics or it didn't happen

(Internet slang, humorous) Used to request a picture of a reported event, especially on an Internet forum. / (Internet slang, humorous) Used to demand verifiable evidence for a statement.

(chiefly Internet slang) Used to indicate that one did not read a (long) text, or to introduce a short summary of an overly long text.

simple past tense and past participle of think one's shit doesn't stink

Contraction of didn't you.

Contraction of didn't you.