Is wearing a bikini and shorts slutty?

So, I'm 16. I was on vacation in FL and i was on the pier in my bikini top and shorts walking to the beach. A guy who appeared to be about 16 or 17 muttered 'slut' as I walked past him. I mena, I am not like, fat, but, im not tiny. so, i really don't know... what do you think?