When your girl wakes up with a huge headache due to the hangover she has attained from the night before, you slap her ass, put your dick in her butthole and hang on for the ride because she will be bucking up and down like a bull thats angry. You will achieve maximum greatness if you manage to stay on until she can't buck anymore. She will then pass out due to the overwhelming heat stroke or anxiety attack of this activity.

When you're being horny (especially around friends) and as a result shame ensues.