Studies show rectal thermometers are still the best way to take a baby's temperature. Plus, it really shows them who's boss.

The line is a characteristically Fey-style joke that fuses mock-authoritative “studies show” rhetoric with an abrupt, taboo domestic image. On the surface it riffs on parenting advice about accurate infant temperature-taking; the punchline turns the clinical act into a comic power struggle, satirizing the insecurity of new parents and the cultural pressure to “do it right.” The humor depends on incongruity—treating a baby like a rival to be dominated—and on Fey’s broader comedic persona of puncturing earnest self-help language with blunt, bodily reality. It also lampoons how easily scientific language can be used to justify almost anything, even an obviously absurd motive.