The story
From teen + baby, by analogy with adult baby; compare TBDL.
Etymology from Wiktionary, CC BY-SA 4.0.
Today it means: A teenager who enjoys role-playing a regression to an infant-like state and acting like a baby or toddler, sometimes for sexual gratification; an adult baby who is a teenager. Full definition →
From teen + baby, by analogy with adult baby; compare TBDL.
Etymology from Wiktionary, CC BY-SA 4.0.