When a young person retires to bed before an age-appropriate time, like an old geezer. Also spelled geezin’ it up. Pronounced with a hard ‘g’ as in ‘gas’.
“Did you make it to midnight on New Years Eve?”
“No, man, my girlfriend and I were geezin it up”.
Short-hand for the word floccinaucinihilipilification, meaning the estimation of something as valueless (encountered mainly as an example of one of the longest words in the English language).