steaming seems a possibility
steaming can be PSISED and PSSied off/angry
steaming is also shoplifting by a large group of youths. Could also be a mugging perhapps.
And steam = muggy.
So several possible links
It's definitely Steaming. Steaming is a sort of mugging on the London Underground, where groups of youths 'steam' through the carriages threatening and robbing from passengers