Mannerisms are part of human life and do not spare anyone - whether or not one plays tennis.
Nadal has long been notorious for pricking his pants before each serve. So much so, Mikhail Youzhny imitated this action - while playing Nadal at the opposite end !! - in a five setter in 2007.
Roger Federer is known for not showing much emotions on court until we saw him sweetly break down in Aussie'09..!!
What would we like our favorite players to stop doing or start doing?