When one friend or colleague adopts the position of standing whilst bent over, or on all fours, in preparation to receive the ejaculate of another colleague or friend to their back region. This ideally should be performed in a public area, such as a high street or shopping district of a well populated town, surrounded by mutual friends or colleagues in order to constitute a ‘full Tanner’. If the latter conditions are not meant, then the action between two friends or colleagues may only be considered a ‘half Tanner’.

To quickly check Wikipedia in order to try to win an argument (over the internet usually). Unintelligent people generally do this to make themselves look smarter than what they are.

A man named Willy had the largest black hairy penis ever. Btw he is a white man

On insertion of the penis into an armpit, (usually not one's own), the recipient rotates the arm windmill-style until the desired consummation is attained.

The act of jerking off outside a window whilst crying as the person commiting the act has come to terms with the fact that they are a pathetic welp of person who looks up vaguely sexual terms on Urban Dictionary to get a hard on, only to quickly be struck with the epiphany that they are wasting the precious life they have been endowed with, and the person you could have been has been burnt into nothingness by your abhorrent choices in life, and you are just the abysmal shell of what could have been a potentially good human being.

When you stick a worm in your urethra and you have to ejaculate it out before it crawls in.

when two or more boys get together and wank each other whilst thinking about girls