A ‘gimme’ - short for "give it to me" - is a putt conceded by an opponent at his discretion when he does not think there is any chance you will miss.
The putt would be too close and too simple to make you go through the motions of finishing the hole.
Only in matchplay golf is this possible, because in strokeplay all shots must be played and a hole has not been completed until the ball is safely in the cup.
Jack Nicklaus famously conceded a tricky putt of Tony Jacklin's on the 18th green at the 1969 Ryder Cup, forcing a tie in the overall contest.
His gesture was seen as generous in the extreme because Jacklin was by no means certain to make the putt, especially at such an important stage of the match and some of Nicklaus' American team-mates were less than pleased with his decision.