Big Daddy eating a Shark Man. (and also completing the mission)
The Shark Men Snack goal is a goal for the Big Daddy which requires to eat 2 Shark Men. This goal is probably moderately hard, because Shark Men aren't super rare later in the game, and they are rather fast (however, Big Daddy has enough speed to catch them).
Strategy[]
Shark Men are found on beaches. He is a person with a shark outfit on. If he sees you, he will very quickly run away. He escapes quickly, so you should be fast. Sometimes while he escapes, he will swim through the water. If you let him go too far, you may not find him. However, if he gets away, you can go to where you originally found him, and he'll still be there.