A gaymog is usually a guy who tries to intimidate other guys by behaving in an over the top homosexual way. A typical gaymogging attempt might include things like hugging, stroking, and talking in a stereotypically gay way, the goal being to get a reaction out of the PUA or creep him out.
Weak gaymogging attempts can usually be ignored, but the best way to diffuse a gaymog is generally by playing along with him and taking things even further, effectively out-gaymogging the gaymog. For example, if a gaymog tries to intimidate a PUA by getting into his personal space and being overly friendly, he could counter by lightly kinoing the gaymog. The ironic thing about most gaymogs is that they are themselves somewhat homophobic, so turning their tactics against them is a great way to diffuse them.
The purpose of a gaymog is to intimidate, so the most important thing to do in the face of one is not to be flustered or react negatively to it in anyway. By keeping a solid frame and humorously using gaymogging tactics himself, a PUA can easily disarm a gaymog.
That douche was trying to gaymog me, so I whispered sweet nothings in his ear and he freaked out and left me alone.