Definition of contact high in US English:

contact high

noun

US
slang
  • A feeling of elation or intoxication influenced by the (especially drug-induced) behaviour or mood of another person; (also) an instance of intoxication caused by (inadvertent) inhalation of smoke from another person's marijuana cigarette, pipe, etc.

Origin

1950s; earliest use found in Jack Kerouac (1922–1969), novelist and poet (real name Jean-Louis Kerouac).