Not a real word, but a mispronounced version of Shifty. Shifty referes to somebody suspiciously looking about themselves as if to make sure they're not being watched.
"...and his sifty eyes were.."
Do you mean shifty!?
"Oh, yeah. Anyway..."
When fifty is the new sixty. When recently healthy and vital people, so exhausted and worn down from Covid, from politics, from the craziness of masks, vaccines, the Big Lie, feel they have lost not just a year but a decade.
Yesterday she was 49. Today was - big whoop - her birthday, and whatever the balloons spelled out, she was sure she must be turning Sifty.