1) When your manhood has come into question, and you challenge the question-er to prove your manliness
2) Any time a person's manliness is said to be insufficient
3) A competion
1) person a- Jim is lucky he's not in a coma! He drank over half a case of beer last night.
person b- What?! Why?
person a- Man Challenge
2) person a- No, it's okay, just carry two, we all know you're a little...
person b- Are you challenging my manhood?
3) Ladies can have Man Challenges too, despite their name, Man Challenges don't see gender.
A summons to prove a man's ability to accomplish a given task forcing him to believe his genitals penis are larger than they are known to be.
Jake failed Susie's man challenge to remember to put the toilet seat down thus Jake faced the harsh reality of his actual penis size small.