I have always thought that the King's Gambit smelled fishy.
What is the worst gambit?

Botez Gambit, give up queen in a losing position and where you lose immediately or try to salvage a draw.

This is actually a very useful gambit and often results in the opponent losing a tool to one of the bishops

englend gambit
this gambit literally forced my openenet to rsign because there are no choices.

I think the worst gambit is the Albin. On lichess.org one time I mouseslipped the Albin against a 2000 lichess elo and I got the trap
0-1
Halloween gambit is the worst