Is it possible to hide a tongue piercing?
If it’s pierced quite far back, you can’t see it unless you stick your tongue out. If you can try and talk and eat as little as possible without raising suspicion, do that for the first week so she doesn’t notice the swelling. Tongue piercings heal so fast you could probably get a tongue-coloured retainer in there after a month or so. I’ve personally found that honesty is the best policy with piercings, beats them getting angry when your parents find out.. So try telling her. Or like, bargain. “If I get this grade… I get a tongue piercing” etc. Make the point that you can barely see it and it heals basically without a scar. If you really are dedicated to getting it, you should wait and respect your mum’s wishes really, but to be honest unless you’re VERY underage there’s nothing she can do to stop you. Good luck!
