How should I tell my parents?

I got my belly button pierced. I'm 18 and I'm leaving for college in two months but we have a family reunion at the beach in 3 weeks. I'm technically allowed to get it done and i wont get in trouble but they'll be disappointed because my dad thinks its trashy. im not a trashy girl...at all..and i dont want him to think poorly of me but i did it anyways. its two days old now so i cant take it out before the beach. is there any way to hide it? i know thats a dumb question but worth a shot. how should i go about telling my parents? my mom wont be mad...should i tell her and make her tell him? helpp...i know this was dumb. please dont tell me that.