1
general::
1. Under the influence of alcohol or a drug. For example, I think he got high on marijuana before he came to the party. [c. 1930] 2. Very enthusiastic about, as in They were high on video games. [1940s]
American Heritage Idioms
2
general::
Phrase(s): high on something
Sl. 1. excited or enthusiastic about something. • Tom is really high on the idea of going to Yellowstone this summer. • I’m not high on going, but I will. 2. intoxicated. • John is acting as if he is high on something. Has he been doing drugs again?
McGrawhill's American Idioms And Phrasal Verbs