What’s your best catcall deterent?

I was just thinking about it and years ago before my husband and I were even engaged.. I was walking to my car and this dude started following me, he was young, probably 18.. he said “hey, what’s up” I said “nothing” and kept walking.. he ran up to meet me and first words were “you got a boyfriend” I said “yes” he said “well come back and chill with me for a minute” I said “no my boyfriend wouldn’t like that” and he says “well you don’t have to tell him everything” and I brandished my knife and said “well I’m going to have to explain to him why I’m in police custody so yeah I’ll have to tell him” never seen a person retreat as quickly as he did 😂😂 it was amazing!! And of course I told my husband(then boyfriend) about it as soon as he got home