gripiest
/ˈɡrɪpiɪst/
adjective
- Most inclined to complain or grumble; most irritable or discontented.
- Of all the hikers, she was the gripiest about the steep trail.
- He was in the gripiest mood I'd ever seen, complaining about everything from the weather to the coffee.
- The gripiest customers always seem to find something wrong with the service.