About Yamcha's scars and how he got them.

[Goku da Silva]

So, this is one of those things the don't change a thing in the story at all but it has always puzzeled me, before the 23º Tenkaichi Budōkai he shows up with this brand new look(tho huge scars in his face) and Toriyama never gave a hint on how he got them. So i want to hear your theories about it.

[Lionel]

They may have come from the training undertaken with Tenshinhan, Krillin, and Chaozu when they climbed Karin's tower together. It's also possible that whatever training they went afterwards on their own caused him to garner scars on his body. If Yamcha chose to branch out and travel the world as Goku did following Karin then it's believable he could have garnered some scars along the way.

[BWri]

Yamcha's cool. Tien's cool. I'd love to learn more about them. Like what they do day to day or how they grew up and learned to fight. I can't imagine how Yamcha would get those scars other than training. Perhaps he was climbing some mountains and fell down it. Or maybe he fell from Kami's Lookout into the trees below.

I can't really see a person doing that to him, unless perhaps he training with Bora. Maybe he had a fierce bout with Tien. They cut each other's face before with strikes (anime).

[Yuli Ban]

The simple answer is "martial artistry." When your life revolves around fighting and combat, you're going to get a few scars. It was probably just some fight that got a little out of hand; all that matters is the scar itself showing that he's developed some amount of experience as a warrior.

[Polyphase Avatron]

Maybe he accidentally ht himself with his own Wolf Fang Fist

[RashFaustinho]

These are not scars. That's just how his face his.

He eats the Senzus, he dies, but the scars are still there.
It's all part of his face. He was born that way.
A monstrous child that since the age of 0 had scars over his face.

[TobyS]

Whats really weird is how by the point in the story he gets them there shouldn't be anyone left outside the main cast who can do it to him.
And if it was one of the main cast it's weird it was never mentioned or shown.

Out of universe Toriyama probably just added them in the same way he changed characters outfits periodically, just slight redesign/alteration, they do look cool, perhaps he never considered the in of universe implications.

[Yuli Ban]

These are not scars. That's just how his face his.

He eats the Senzus, he dies, but the scars are still there.
It's all part of his face. He was born that way.
A monstrous child that since the age of 0 had scars over his face.

This is probably the truth.