The only base you can slide into where you KNOW you'll get your pants muddy.
Brian: How far'd ya get with her?
Mike: Fifth base!
Mike: Yeah, this mourning I totally had to wash the uniform.
Usually involving more than one offender.
Brian: Hey Mike were you at that party last night?
Mike: No, what happened?
Brian: A stripper came over and these Lacrosse players were totally Dukein' her!