Muppet is actually a widely used derisive term in England. It's applied to MUP users because of the MUP root and because you see a lot of people doing unpredictable things on MUPs. The ones here in Vancouver aren't so bad as they're hardly used, but get into Porltand on a sunny day and they're downright dangerous to ride at anything over 8 mph. Lately I've begun to commute on the Portland MUP @ 6am and that's not so bad since pretty much everyone on at that hour is a pro with someplace to go. 15mph is relatively safe at that hour.
The 41 is code for the Road Cycling subforum. From the main page you can hover over the subforum links and discover all the codes.
Here's the url for Road Cycling:
We are currently posting in the 7.