The other fun one to swap is 'more' with 'mroe', at school someone create a 'mroe' command that returned lines from the file by swapping every second and third line in the output, that lead to folks adding 'alias mroe more' in their .cshrc files :-)
that is awesome, will make a video about that one this upcoming week.
I head that there is also one for service, it might be considered not political correct and offensive by some but it basically works when one misspells the word "restart" in `service XXXX retart`
It is the perfect prank for multi-users environments. I mean it is funny and not as bad as an alias to `rm -Rf`. It might make you win a one way trip to HHRR with no return tho.
Fun fact: `sl`, `sl -a`, `sl -l` and `sl -F` produce different trains.
I was sure that everyone knew about this already...