The filter in guys' brains which keeps unspoken love and affection for one another unspoken, as it should be.
When a guy shows way too much physical and verbal affection for another guy, making otherwise normal situations and interactions creepy, awkward and uncomfortable, he has ignored his Dude Filter:
-Extra long hugs.
-Telling a guy he's sweet and you love him.
-Talking way too close to him.