"Crybaby" is the sister of "Badcall" Benny, and, like her brother, plays against Snoopy and Molly Volley in the tennis doubles. Hence her nickname, she tends to complain a lot. She also seems to care (at least a bit) for brother's well-being, as seen when she yelled angrily at an even-angrier Molly Volley for hitting his mouth ("You hit my brother in the mouth!").
"Crybaby" Boobie usually wears a polka dotted tennis dress (colored pink in animation). Her specialty on the tennis court is whining about how everything is unfair (except when she wins a game), hence her nickname, "Crybaby". The humor in Peanuts comic strips featuring "Crybaby" Boobie sometimes comes from her complaining about two contradictory things in one strip, (for example, first she complains that it is too hot, but in the next panel she complains that it is too cold). The only thing that seems to quiet her down is a punch or kick from Snoopy or being told to shut up by Molly Volley. She is rarely shown with a full face, rather she appears as a large open mouth with hair coming out each side, as if she has her head tilted back so as to complain very loudly. However, when she wins a match, her head is still tilted back, but she then has a smile on her face.
She has a brother, named "Badcall" Benny who first appeared on April 16, 1982 and is more sedate than she is. She has a huge fan in her stage-door mother, who often honks her car horn whenever "Crybaby" makes a good shot (Molly responds to this in one strip by tearing a hubcap off the car.). Almost every time other characters hear her name mentioned, their reaction is "Crybaby Boobie???"
Her last appearance was on March 10, 1997 in a match against Snoopy, where her face is shown for the first and only time, when Snoopy kicks her foot. This reveals her eyes are black dots, as is the case for most characters.
She also has a brother named Bobby Boobie who is never seen.