I've actually done this for a couple commands I screw up often enough -- I have this in my bashrc:
alias dumbtypo="echo 'LEARN TO TYPE, MORON'"
alias sl="dumbtypo; ls"
alias rbuy="dumbtypo; ruby"
alias pytohn="dumbtypo; python"
alias brwe="dumbtypo; brew"
alias arhcey="dumbtypo; archey"