The sign for teenager is related to the signs for MAN, WOMAN, DAD, MOM and similar signs. "Teenager" is done by touching a "T" handshape to the side of the chin and then to the side of the forehead.
TEENAGER:
Note: There is a version of this sign that uses an "A" handshape and is interpreted as "adult." Some ASL teachers consider that sign for "adult" to be Signed English rather than ASL and they prefer to use the bent-hand non-inflected version of TALL to mean "adult." See: ADULT
Also see: YOUNG which is sometimes interpreted as "youth" and can be used in the phrase "young people."
Notes: