When the motivation gives you a massive erection. Both men and women can have moto-boners.
As Sergeant Brown mowed down some Haji faget fucks with his .50 caliber machine gun he began to grow a moto-boner. He then proceeded to spit the juices from his chewing tobacco onto his hand and slowly move his hand down his pants.
A woman who is physically attractive, but totally kills your boner (attraction) due to her negative attitude and lack of intelligence
Hey François that girl I went on a date with last night was a TBK (Total Boner Killer) bro. She was gorgeous until she talked about how much she hated her job."