I hate the stigma around bad trips. They are really almost non-existent... it's only going to happen if you will it to happen, and that's pretty damn fucking likely when all you know about psychedelics is that they can give you a bad trip.
In reality, you might think of a scary monster, then you come to terms with the unreality of the monster, and begin to dissect the evilness away until you are left with a lonely little kid inside that monster who just wants out.. then you realize the monster was you all along, and that the "scariness" was just the evil and misdirection that makes up your life...
um... that was a bit off topic. But no, you should NEVER EVER EVER roll or take drugs just for the hell of it (especially not psychedelics

that might be the only thing that's caused a bad trip for me. Taking them just for the fun of it)
Maybe get drunk and smoke some weed, but when you can only roll once every 3 months, you don't waste that shit.