I don't know about the most outlandish but the most "I can't belive I've just seen that" pub name I recall is one in Norfolk which, certainly up until I left the county a few years ago, had a pub called "The Labour In Vain". Nothing wrong with that you may think - except the pub sign was a painting of a little black boy in a bath being scrubbed by a white lady.
You. Couldn't. Make. It. Up.
In Rugeley there was (may still be although it's been a few years since I went to that part of town) a pub called "The Comet" which when I lived in a neighbouring village had a lovely sign outside of "That Airplane". The pub was apparently built in the 1950s and was named after the first jet airliner. However, the stupid brewery (Ansells if I recall) decided in the 1990s to refurbish it and replace the sign with a painting of a Comet (Celestial phenomenon). Amazingly the locals all complained and eventually the brewery relented and put back the original sign complete with new painting of a Comet 1!
Here are a few I lifted from the BBC Radio Lancashire web site:
1. Hark to Bounty, Slaidburn
2. Tinker and Budget, Oswaldtwistle
3. Clog and Billycock, Blackburn
4. Doctor Syntax, Preston
5. Hand and Dagger, Treales
6. Snig's Foot, Ormskirk
7. The Cock and Bottle, Tarleton
8. The Crooked Billet Inn, Worsthorne
9. The Duck and Puddle, Blackburn
10. Fibber McGees, Lancaster
I like Doctor Syntax and I am very curious as to what is on the sign outside The Cock and Bottle" ;-)