the complete length of the penis inside the anus/vagina. its the absolute fullest length and includes all the penis and even some of the skin around it.
"hakko got the full length from me! ahahaha" - Macho tiger
British slang defining the result when one manages to get rid of the entire contents of their rectal passage in one go, without splitting the fecal matter in any place or having to do 'seconds' (where there is more than one log).
"Scott managed to squeeze off a full length on Monday."