Note how Piccolo's blood was red here. This part (and in DBZ when Raditz blasted his arm off) were the only two times in the original DBZ where Piccolo had red blood. This was because he was meant to be a demon before AT (Akira Toriyama) got the idea to say he was an alien (which would later reveal that Nameks have purple blood).
Piccolo: Your arrogance is astounding. You really believe you can beat me!? BEAT ME!?
Piccolo: You fool! Are you simply so moronic, so moronic that you can't comprehend the impossible odds before you!? I am infinitely better than I was 3 years ago!
Goku: 3 years is a long time, and you're the fool if you think I haven't changed as well.
Piccolo: BE QUIET!!
Krillin: Don't worry. We're a team. If things get too bad, we'll take out Junior together!
Piccolo: Hahaha! Good one! Your friends are so loyal...and foolish. A bunch of inept weaklings coming to the rescue of their idol, I'd pay a zenny to see that!
Kami: Before we proceed, think this through very carefully. If we act now we can stop him together, there may not be a second chance.
Goku: Thanks for your concern. But I've made my decision. I have to defeat him alone. It's just something I must do.
Original Air Date: February 22nd, 1989
Japanese Title: Son Goku's Trap