Among Nintendo fans, there has been dispute as to whether Mario was telling Yoshi to get something or smacking the character in the head. According to Nintendo, Mario was originally punching Yoshi, causing the character’s tongue to shoot out in surprise.
For example, a few years back website Supper Mario Broth tried to disprove the Mario-is-punching-Yoshi theory with the images below, explaining that “Yoshi contorts his face before Mario’s hand overlaps his head” and that “official art suggests Mario is simply pointing forward to show Yoshi what to lick.”
[GIF via Supper Mario Broth]
[Image via Supper Mario Broth]
According to Tezuka, Shigeru Miyamoto said he wanted Mario to ride a horse. “I think he likes horses,” Tezuka added. “When we were making [Super Mario Bros. 3], he drew a picture of Mario riding a horse and had put it up on wall next to where he sits. When I saw that, I thought, ‘I guess he wants Mario to ride something.’ So, when we were making Super Mario World, we had this ‘dinosaur land’ concept, and I had Hino draw reptile type art.”
“Initially,” Hino said, “the keyword that I had was ‘horse,’ so I imagined something quite later and, for the time being, drew a large lizard type creature.”
“It looked like a crocodile,” explained Tezuka, who felt like a reptile-looking creature might seem out of place in Mario. Tezuka drew a rough sketch of a cute character and on the basis of that, Hino created Yoshi.
“Lots of people think that while Mario is pointing his finger forward, he’s saying ‘Go,’ and Yoshi’s tongue comes out,” said Hino. “However, the set up that I drew was that when Mario punches Yoshi in the head, the character’s tongue shoots out in surprise.”
“What’s more,” Hino continued, “there’s an added ‘bop’ sound. However, it seemed like people would say ‘Poor Yoshi,’ so that’s why it became that Mario is saying ‘Go.’”
This explains why the official line is that Mario is telling Yoshi to go or get something, but the original art shows Mario smacking the character in the head.