Trolling is using actual debate tactics to trap someone into an unwinnable argument, therefore totally wasting your time.
Acting stupid and afterwards saying 'umad' is not trolling. That's being an imbecile.
Laughing at trolls (the fake kind) means that they get what they want, namely attention. You can't "win" against [fake] trolls unless you simply ignore them, a talent very very very few possess.