i. the process of not being grumpy anymore, and
ii. the transitioning and gradual unpeeling into the state of ungrumpiness.
I get grumpy easily, but I can also ungrumpetise easily
Noun:- (plural)
1. Those that consume alcoholic beverages and inhabit an extrovert, boisterous (and commonly aggressive) nature when the sun is out - mostly persons from a 'chavvy' background.
"It's quite a nice day today, do you think there will be any 'sunshine wankers' around?