A day made up by closeted gay men who aren't ready to fully come out, but are also incapable of masking their homoerotic desires for more than 6 days a week.
Oh my gawd, you have you seen that dude's body? I totally beat off to him today -- no homo, though, because it's man crush Monday!
A hardo is a person who tries extremely hard at everything. Most times a hardo will try very hard at things that do not require excessive effort. For example, sports practices, gym class, etc.
Wow did you see Jack at practice today? What a hardo!