From Rocky Horror Picture Show.

Refers to "wearing" rose-tinted glasses...the old saying is when you see the world through "rose-tinted glasses" (metaphorically), everything is rosy, optimistic.

or from alt.cult-movies.rocky-horror:
Looking at the world with a "rosy" outlook -- in short, a cockeyed optimistic. Not seeing the reality. Or seeing reality, but finding something "good" in everything and not facing or acknowledging the negative.

Or, as another on the newsgroup explained to me:

It describes an acid trip from beginning to end. Columbia describes the want of an acid trip, Rocky proclaims the time it takes to actually peak out (7 hours) and the euphoric feeling. Brad then describes the sudden highs and lows of the trip, and what makes it suddenly phase in and out as the chemical diminishes. Finally Janet describes the coming down from a groovy high, and that it the drug makes you want it again, and again.