1) The last Monday in May on which we get the day off 'cause it was Queen Victoria's birthday like a thousand years ago, whoever she was. Now called 'May two-four'
2) The official start of Canadian summer.
3) The day Canadians drink beer and clean out/open their swimming pools. (weather permitting)
4) a day off at the end of May. The Monday or Friday closest to the 24th, sometimes both.
guy: "why do they call it Victoria Day?"
dude: "idk. who cares? It's may two-four, bitch!"