Stimulated; made to be or feel more awake, alert, and energetic. Hyphenated if used before a noun. I just can't focus until I get pepped up with a bit of coffee in the morning. The officer suspected that the pepped-up truck driver might have been high on amphetamines.

Alert, enthusiastic, and energetic. A: "You're looking very peppy this morning!" B: "I just received some amazing news, so I'm in a great mood!" I've got three kids under the age of five—I haven't felt peppy in years!