1.verbTo behave geekishly or in a socially awkward manner, especially when under the influence of drugs or other psycho-active substances, and exhibiting such marked characteristics as hyperactivity, repetitiveness, talkativeness, nervousness, irritability, or paranoia.
"Hey, check out that guy...he's really geeking out pretty bad."
2.verbTo look; to peep; to stare about intently.
3.adjectiveUnder the psychological effects of a mood-affecting drug; high; stoned