Peanuts by Charles Schulz for February 12, 1977
Transcript:
Sally stands in front of the class. She holds her hand over Woodstock's face and says, "Okay, pilot, thanks again . . . That was fascinating, wasn't it, class?"<BR><BR> Sally tosses Woodstock and says, "And now, as our pilot departs, we have one more surprise . . ."<BR><BR> Sally smiles and continues, "If you'll all go to the windows, you'll be able to see him take off in his famous helicopter!"<BR><BR> Snoopy, as a helicopter, flies away. Woodstock is the pilot.<BR><BR>
I think he was giving her the bird as he flew off!