I love needing to grep thousands of files in 50 dot-directories recursively, and my first clue the 50yo ".*" gotcha bit me is a read-permission error for a file in an ancestor directory after a long wait.
Related, I once accidentally pwned an entire college lab of NeXTstations without touching a keyboard.
My home directory's ownership got messed up, the sysadmin was struggling to catch all my files in the fix commands, and I pointed out that my home dir's dotfiles needed the fix as well. The sysadmin got bit by the same ".*" bug on that 1992 day I got bit by today, but on the chown command.
