1. The hour of the day known as Rush-hour when there are an awful lot of people driving like bastards and nearly running you off the road.
2. the hour following the Weekend pub-crawl when all the students / drunkards / louts / ne'er-do-wells are completely twatted and getting rowdy in the streets.
1. Oh Fuck, we're 20 miles from home and we've hit Twat Hour. This guy's driving up my arse, the wanker.
2. Look at all those pissed students stumbling out of the Red Lion. Looks like something's about to kick off. Must be Twat Hour.