Definition of slowroll
A slowroll is a mischievous move we make for titler our opponent. A slowroll is when you take your time before calling a bet when you have the best possible hand. The goal is to have an "mind game" with your opponent. Imagine that you suspect a player is pushing all in often against you in a bluff. Each time, you don't have a good enough hand to call, but his aggression irritates you. To get revenge, you decide that the next time you get nuts, you'll pretend to hesitate to call. He will be anxious to know whether or not his bluff will be called.
Slowroll is legal, but immoral
Of course, there is no regulation against the slowroll. If you want to do it and waste your bank of time on a slowroll, it's up to you. However, apart from irritating your opponent, everyone will lose. The game is legal, but clearly immoral. You will lose your reputation and will probably be seen as an undesirable person at the table. When you have a nuts and someone pushes all in, go for a snap call!