He has a punch like a mule

The speaker meant to say “kick like a mule” (kick very hard) so we know this is one phrase in the mash-up, but what was she thinking when she said “punch”?  “Punched out” comes to mind, but also “punch like a girl” (soft hitting) also could have been in the subconscious, particularly since the words “girl” and “mule” are both four letters long and end with the L sound.  All I know is when I heard it something just didn’t sound right, a true endorsement for a good malaphor.