Why not? Several reasons.
Because it likely won't be as effective, and likely will come off. and if it is the only bc you are using, it is as if you had unprotected sex.
And condoms are only 87% effective anyway... for sure good, but you won't then be able to see if it leaked, and thus won't know if you ought to find someone 18+ to then buy you plan B
(Which you ought to have around anyway), and as well, she ought to be on the pill...bc is free at Planned Parenthood, and they don't even call your parents.
So, yes, you for sure can use one in a spa, but it might not prevent a pregnancy .
Hon, you get a lot of bad information from the 12 and 13 year old who do the major answering on this site..............