Two for One

 is the nineteenth episode of the fourth season and the seventy-sixth overall.

Synopsis
While Doc examines Tucker inside Blue Base, the Reds digress into a discussion on the relative appropriateness of hand to hand combat, sniping, and nuclear warfare. Eventually, Sarge, with Lopez's head in tow, heads out to steal Andy from the Blues.

Doc returns outside to give Church and Caboose his diagnosis of Tucker. After prolonging his explanation of Tucker's condition for dramatic effect, he discloses that he believes Tucker is pregnant, based on the presence of two different heartbeats. Incredulous, Church goes with Doc to confirm the diagnosis, leaving Caboose alone with Andy.

When Caboose has his back turned, Sarge surreptitiously swaps Lopez's head for Andy, leaving Caboose under the impression that Andy had become a "real boy". Shortly realizing that Andy is useless without Lopez, Sarge returns, distracts Caboose, and swaps Lopez's head for a skull. Upon seeing the skull, Caboose believes that Andy has died and, in hysteria, delivers an extended soliloquy lamenting the loss of Andy.