Aliases are extremely literal. If you alias "pop" to "fold sneaky pete's leather jacket (collar popped)", then learn that fuzzy matching exists and try typing "fold pete jack pop" instead, the cli will interpret that as "fold pete jack fold sneaky pete's leather jacket (collar popped)" and fail, but "fold pete jack popp" works fine.
A good plan is to unalias anything you expect to type in any context other than calling the alias, as well as anything that might be a CLI or ASH command you don't know about. (I once had "case" aliased to "display put *". This caused quite a few problems until I realized what was going on.)