As part of the singlish vocabulary, 'issit' is a term that replaces the two english words 'is' and 'it' when used in a question.
"Fuccckkking hungry and bored lah..."
"At nine'o'clock go bubble tea and karaoke issit?"
Amalgamation of the words "is" and "it", used either to(worryingly)signify an exclamation or to a question in itself.
Highly meaningless expression favoured by both chavs and certain asian/black cultures often found within a similarly indecipherable banter.
Shreena - "Oh ma gosh! He was like, all ova her and like, she was like, geet off me! Like.."
Rita - "Awwww, issit?"
Shreena - "Yea, and I'm like, daz sum ova sheet..."