Youthasizing is the process of reducing someone's biological age, through spa treatment including botulism injections, massage, and immersion in a searing-hot tar pit containing time-altering chronotons.
Hermes: We've decided to do the merciful thing and have you youthasized.
Farnsworth: Dear God, no!
Amy: Oh, relax, Professor. "Youthasizing" is a trendy, new spa treatment. It's this season's shark-cartilage enema.
Heather: Since this is such a serious case of old, we'll have to try our strongest treatment: a soothing full-body bath in searing-hot tar. [She indicates the pits.] Sir, it's not necessary or wise to be naked.
Farnsworth: You sound just like my tennis instructor. [He climbs into the tar.]
Heather: The tar blisters the age right out of the body in what top scientists suspect is a miracle.