'How exactly does someone "dress like an arsehole"?' Just guessing, as a random sample of the ways some people choose to dress in the UK. Wearing pyjamas and

'How exactly does someone "dress like an arsehole"?' Just guessing, as a random sample of the ways some people choose to dress in the UK. Wearing pyjamas and bathrobe in the supermarkt? Wearing sports clothing despite looking like they don't ever actually do any sports? Wearing trousers/jeans that don't go all the way up to the waist?