If you do this you could end up owing significantly more on your taxes, because then you’ll be responsible for all of the social security, Medicare, and income taxes on your undeclared tips, in addition to a penalty equal to 50 percent of those social security/Medicare taxes. Plus, if your tipped income is significant, you could also face penalties and fees for an underpayment on your taxes. Definitely wouldn’t recommend this strategy unless you have a good reason for it.
Sources:
$1;
$1 (PDF)