Slang for semen. Sometimes sold as merchandise (mugs, t-shirts, etc) and purchased by women to low key indicate they perform oral sex.
Nick: What did you get Jennifer for her birthday?
Joe: I bought her a male tears mug. She earned it after the blowjob she gave me last week.
Jack: I'm going to ask Jill if she'll be in our bukkake.
Kurt: Jill is into that sort of thing?
Jack: Yeah, haven't you seen her "I bathe in male tears" shirt?