Two examples of English gay slang that seem appropriate here:
"Oh, Mary, please..." (sarcastically expresses Серьёзно?!, or С меня хватит! -- a bit old-fashioned, but still heard)
drama queen -- someone who is ALWAYS "over-the-top"
Neither of these seems to have equivalents in Russian gay slang, however. (But English speakers might be interested to know that "Он в теме?" is basically equivalent to "Is he a friend of Dorothy?" -- i.e., a coded way of saying "Is he gay?")