RT's is short for Retard Tingles, or the sensation one gets after watching something painfully embarrassing and stupid. This type of feeling usually follows incredibly dumb commercials, music videos, embarrassing home movies, or Animal Planet.
"Ew, man, a Fitness Made Simple commercial."
"RT's dude, RT's."
Rock Tit's, When a girls nipples are so hard you can see them through her shirt. Often happens in the cold or if a girl has more pokey nipples and doesnt wear a bra. May even happen during erousal of a woman. Many guys get RT's too in cold.
John: "Oh man did you see Madi's RT's?"
Alex: "Yeah those are Bonerific!"