Putting humans on the moon was serious business. But decades after NASA's Apollo missions, people are having some laughs over transcripts of astronauts' humorous conversations aboard the spacecraft. The source of the zero-G levity? Poop jokes.

For all their technological sophistication, the Apollo command module had a relatively primitive system for managing human waste. Astronauts deposited their feces in "a plastic bag which was taped to the buttocks."

Perhaps unsurprisingly, the system didn't always work as envisioned. One problem the astronauts made light of: "Turds" that occasionally floated through the capsule.

A transcript of the 1969 Apollo 10 mission, manned by commander Tom Stafford, lunar module pilot Gene Cernan, and command module pilot John Young, is reminiscent of the classic scene in "Caddyshack" in which a candy bar is mistaken for a "doodie."

"Oh -- Who did it?" Tom Stafford asks at one point. Confused, Young and Cernan reply, "Who did what?"

Cernan: "Where did that come from?"

Stafford: "Get me a napkin quick. There's a turd floating through the air."

Young: "I didn't do it. It ain't one of mine."

Cernan: "I don't think it's one of mine."

Stafford: "Mine was a little more sticky than that. Throw that away."

Young: "God Almighty"

(laughter)

Though the transcripts have been declassified for quite some time, NBC reported, news of floating "number two's" aboard Apollo 10 has recently resurfaced on sites such as Reddit.

During another instance, Cernan is apparently interrupted by another "floater" mid-sentence.

Cernan: "Here's another goddam turd. What's the matter with you guys? Here, give me a --"

(laughter from Young and Stafford)

Stafford: "It was just floating around?"

Cernan: "Yes."

Stafford (laughing): "Mine was stickier than that."

Young: "Mine was too. It hit that bag --"

Cernan: "I don't know whose that is. I can neither claim it nor disclaim it (laughter)."

Young: "What the hell is going on here?"

All jokes aside, Apollo 10 was by all counts a successful mission. Stafford, Young and Cernan paved the way for future moon landings by piloting a separate lunar module to within 9 miles of moon's surface and back. According to NASA, all mission objectives for Apollo 10 were achieved.