My Lovely Horse, every time. "We have to lose that sax solo!" 
I've been rewatching lots of One Foot in the Grave - far too many moments that still have me laughing including the wig in the loaf of bread, the puppy instead of the phone and this ridiculous gem below. It's the response of Mrs Warboys at around 1:30 that cracks me up 
Retro and Northern Ireland specific - clips of James Young and Julian Simmons for a bit of nostalgia. "But now on the UTV!" 
Dave Spikey in Phoenix Nights when he's on the Pro Plus and sake, particularly when doing the bingo and Chitty Chitty Bang Bang. I often use this as an analogy for how my ADHD affects me - that it can be like this followed by my brain functioning as well as Norman Collier's faulty microphone 
And Sammy Snake, definitely NSFW 
For anyone who likes Sean Lock he did a show called "TV's Believe It Or Not" a few years back on BBC4 looking at some weird UK TV from the past. For some reason there's a bit from a very old live episode of The Sky At Night that keeps going wrong. The way Sean keeps going on about "liiiiive ASTRONOMEEEE!" always makes me laugh 
And another Sean - the absurdity of Sean's Show 