1. To act in a homosexual manner. 2. To behave, dress, perform or act in a way that would lead others to think one was a homosexual. 3. Metrosexual behavior would be considered acting in a "homosexualishly" manner. 4. Substitute term to replace the phrase "acting like a homo".
"Bryan is crazy about that Kristin girl but every time he is around her, he starts behaving homosexualishly and now she thinks he's a fag.