Too much PDA?

My husband likes to show PDA alot he like kisses me on my neck and rubs my thighs and if I'm wearing a skirt or something he'll put his hand up my skirt and he makes out with me very roughly....I'll just say " honey people are watching" and he'll say "who cares" why is he overly affectionate in public and how can I get him to stop without making a scene??