water wanker
A water wanker is one of those annoying people who uses very frequent breaks for water (and making everyone else wait) as an excuse to avoid/have time to recover because they can't hack a pace of a game/sport/workout.
Can we just play this game please?
No we can't because John is having yet another drink break - what a water wanker!
No we can't because John is having yet another drink break - what a water wanker!