April fool
noun
1
a tool. Rhyming slang, originally meaning a burglar's tool then in more general use as a workman's tool UK, 1960.
2
a weapon such as a handgun, knife, etc. Rhyming slang; a narrower sense of the much earlier 'tool' UK, 2002.
3
a stool, usually a bar stool. Rhyming slang UK, 1960