The 33-year-old model and television personality and Fallon, the host of The Tonight Show, tried to identify the objects by touch during a game of Can You Feel It?
Fallon went first, sticking his hand into a box filled with unwrapped sticks of butter, and correctly identified the item. Teigen went next and got grossed out as she gingerly touched a sand castle.
"What was that?!" she yelped. "Oh god, is it an ant farm?"
Fallon's next object was a live lungfish submerged in water. The late-night host eventually touched the fish but was thoroughly freaked out.
"Are you joking me? That is not in the rules at all or any respect for me at all!" he exclaimed. "What is a lungfish?"
Teigen got a scare with her next item -- a dinosaur grabber souvenir that someone was operating from under the table. The toy "bit" her fingers as she touched it, leading to a big scream.
"It bit me!" she said.
"Your mouth is just wet and perspiring," the star recalled. "I had to go to the hospital, and my tongue was stripped ... it was bloody and stripped and I had acid reflux for a long time."
"I licked them," she explained. "That was a mistake."