The odd sensations you feel after taking a slow-acting drug (such as ecstasy, mushrooms, or LSD) but before the effects have truly set in. The knowledge that something about your body and perceptions have changed even though you can't fully grasp what has changed about them. The confusing mix of nervousness and excitement that transitions into the actual drug experience.
Yo, I don't know if I should have take that ecstasy. I'm nervous and can't stop pacing around the room.
Relax, it's okay. You have the weirds. They'll go away in a few minutes and you'll be rolling and feeling great.