Context High

"Feeling" the effects of drug inebriation through proximity rather than through actual ingestion.

In other words, feeling high because people nearby are high, despite not actually having taken any drugs.

"I wish I hadn't said that out lout to everyone at the party, but I wasn't in my right mind."
"Were you high?"
"Not exactly, but everyone else was, so I ended up feeling a context high."

Context High

The act of developing and being part of an inside joke.

Man, this joke gives me a good context high.