You shouldn't discriminate against people with lisps.
Mary is the judge of a singing contest right now, and some of the contestants have lisps.
Mary wants to pick a singing contestant as a winner.
Mary ignores the fact that some of her contestants have lisps and lets a few contestants with lisps win.
Mary explains that all participants with lisps are automatically disqualified from winning.
Mary's contestants feel the competition was fair and didn't discriminate based on trivial mouth noises.
Mary's contestants are all bewildered at the requirement and gossip about Mary.