The New Addams Family (1998)

S1E12 Thing is Missing

It’s Thing’s birthday, but as he opens Fester’s mail, he’s met with shouts from Fester and the family, who’ve completely forgotten about the occasion. Hurt and upset, Thing decides to leave. Meanwhile, the tension from the argument causes Fester to unexpectedly sprout hair on his head, a bizarre reaction to the stress of the situation.