No, it’s not the first line of a bad joke.  According to the Daily Mail:

Bus drivers have nicknamed a white cat Macavity after it has started using the No 331 several mornings a week.

The feline, which has a purple collar, gets onto the busy Walsall to Wolverhampton bus at the same stop most mornings – he then jumps off at the next stop 400m down the road, near a fish and chip shop.

I don’t quite get the nickname, but the rest of it is oddly fascinating.  I can totally imagine Kahlua getting on the Number 11 and heading over to a diner.