Doonesbury by Garry Trudeau for July 26, 1980
Transcript:
Zonker: Hey, B.D, what are you doing here? Are you going to register? B.D: Register? Ha! Think again, suckers - I'm a vet! If you pinheads had been smart enough to pay your dues in Vietnam, like me, you wouldn't be in this mess! Mike: He's right. What a lost opportunity. Zonker: You sly dog. You knew this was going to happen! B.D: Damn straight.
So BD did serve in vietnam… but they’re all still 20-something year olds. That definitely clears it up, GT.