Other source:
Just to have some fun, Vegeta and Nappa grow some weird creatures, called Saibamen, to test their opponents' strength. Suddenly, Tien, Chiaotzu, and Yamcha arrive to join the battle. Tien is the first to go up against one of the Saibamen. They may be strong, but thanks to his training, Tien easily beats one of them. Angry at his failure, Vegeta destroys the losing Saibaman. Yamcha is up against the next Saibaman, and it seems he, too, is stronger, but his opponent grabs Yamcha and self-destructs.
