in a lip lock

in a lip-lock

slang Engaged in a long kiss. A: "Do you really think Sarah and Andrew got back together?" B: "Yes! I just saw them in a total lip-lock outside the library!"
Farlex Dictionary of Idioms.

in a lip lock

mod. kissing. (Contrived.) They were rhapsodizing in a lip lock when we came in.
See also: lip, lock
McGraw-Hill's Dictionary of American Slang and Colloquial Expressions
See also:
  • in a lip-lock
  • lock
  • pucker up
  • KISS principle
  • curl (one's) lip
  • curl your lip
  • KISS rule
  • kiss something goodbye
  • kiss (someone or something) goodbye
  • kiss goodbye