The way to protect yourself from everything from nuclear attacks to volcano explosions in the mid 20th century.

a sex position that involves a man ducking under a woman's legs and covering his head by inserting it gently into a woman's vagina for a period of time

An excessively risky sexual maneuver performed between a man and women or, alternatively, a man and man whilst operating a motor vehicle. In a role reversal of the classic 'road head' the vehicles operator 'ducks' into the passengers lap to perform felatio whilst the passenger 'covers' (ie; takes control of the steering mechanism) until climax and/or satisfaction has been reached.