That does it, Charlie Brown! He's your dog, and you're welcome to him!

[last lines] Linus:
[outraged by a note handed out by Snoopy]
Look at this, Charlie Brown! Charlie Brown:
[reading it]
"To Linus Van Pelt: I expect my croquet set and chess set returned forthwith, in good order, and within five days, or the matter will be turned over to my attorney." Schroeder:
[outraged over his own note from Snoopy]
And mine says... he wants the record collection back! Charlie Brown:
[reading his own letter]
And mine says... that since he gave me nothing, I owe him nothing! [glares at Snoopy] Lucy:
That does it, Charlie Brown! He's your dog, and you're welcome to him! [everyone walks out on Charlie Brown, Snoopy, and Woodstock; Charlie, annoyed at Snoopy, follows suit]