Robert Picardo is caught in a strange time warp: He can't seem to get out of the '60s.

On "The Wonder Years" (airing Tuesdays on ABC), he has a recurring role as quintessential junior-high-school gym teacher Mr. Cutlip.

And on "China Beach," the Vietnam-based series that returns to the ABC schedule on Wednesday, he plays wisecracking gynecologist Dick Richard, whose heart, in Picardo's words, "is beating in the wings for Nurse McMurphy (Dana Delany)."

Picardo, 36, remembers the '60s well, and his own age conveniently straddles both series. He is a few years older than the kids he coaches on "The Wonder Years" would be today, but a few years too young to have felt the full force of the Vietnam draft, as did the soldiers in "China Beach." Yet, he was close enough to both to be able to identify fully.

"I have to admit I absolutely love going from one show to the other," he said. "Obviously 'China Beach' is the better role; it's a more layered character, and I get to play all different things. But I really relish those moments of playing such an out-and-out geek like Mr. Cutlip. I don't remember actually creating the character. He sort of came out of me. The moment I put the whistle and the cap on, he comes from some deep recess of my soul."

Many of Dr. Dick's wisecracks are ad libs thought up by Picardo.

"Usually, if I can make Dana laugh, they keep it in," he said. "But I only ad lib at the end of the take, so they can cut it out."

On "The Wonder Years," it's different.

"They're real touchy about that," he laughed. "If I make a suggestion, I'm very diplomatic about it. But it gives you something to do while you're waiting. I'm not doing it because I don't think the script is great. It's because you're sitting there four hours waiting for the shot. What else are you going to do?"

Picardo lived through the '60s and is reliving the period on two series. He still has mixed feelings about the era.

"The fact that we were encouraged to follow our conscience and not to follow the crowds -- that's something I really miss," he said. "On the other hand, there were things that drove me nuts in the '60s. There was an aspect of the hippie movement that everyone is an artist, which is lethal. I mean, I sat through more bad theater, because 'anyone is an actor,' and it's just not true."