Green’s Dictionary of Slang

1. (drugs) LSD.

1969

R.R. Lingeman Drugs from A to Z (1970).

2. an LSD guide.

1982

AS LVII:4 289: A guide does not use drugs during parties but serves as a controller, known variously as groundman, babysitter, tour guide, co-pilot, ground control, guru, travel agent, or just sitter.

3. an LSD supplier.

1965		P. Wylie Esquire July 44–45: travel agent — a person who provides LSD.
1969		R.R. Lingeman Drugs from A to Z (1970).
2001		ONDCP Street Terms 21: Travel agent — LSD supplier.