The use of the thumb to 'ease the passage' when partaking of anal with a lady, if you're a real gentleman you may even wet your thumb beforehand.
The thumb must be inserted lengthways (nail to knuckle), and not as in the thumbs up sign, as that is definitely NOT the Gentleman's Way.
The term was first used on a train journey from Birmingham to Manchester in 2009.
It is growing in popularity and has been seen on Facebook and mentioned elsewhere.
He's a nice guy he uses the Gentleman's Way with every lady that he does anally.