I TRIED CONVINCING MY MOM BUT SHE ALWAYS SAY THAT IT LOOKS DISGUSTING AND SHE WON'T LOOK AT ME IF I DID IT. MY DAD WAS OK WITH IT BUT MY MOM ISNT. HELP
Just explain to her why you want one and offer to work for it or pay for it yourself. If she says no then there isn't anything you can do about it until you're old enough to get it yourself. Lip piercings most likely will cause permanent scar though and can get infected.
Explain it not permanent it an expression of your individuality. Its not like a tattoo which you have to live with for your entire life. Just tell her you understand her concerns however, just as clothes are a fashion statement so are piercings