Boner trouble

You turn the heat up in the room a little, and smile as Mike does nothing but stare at his sister's bare legs.

"Dude, don't be a perv," Rose complains, "how'd you like it if I started at your...." Her voice trails off a little as she looks down at her brothers crotch suddenly spotting the huge tent forming in his jeans. "Oh my God, have you got a boner?"