Try dangling the food against his mouth first to see if he will eat it. If not, you will have to force open his mouth and place the food in it. It's easier if you have two people, but you can do it with one. Gently remove your frog and place it on some damp paper towels (spray with De-chlorinated water). He might try to jump away so if you have him on a high surface like a table or counter top be very careful. They can and will jump great distances. Have the worm or food ready. Use a credit card or shopper card to carefully put pressure against his lower jaw. You'll want to insert the card over towards the side of his mouth but not all the way at the corner of the mouth... sort of below the eye. It is helpful to have a second person to hold the frog steady; it will try to back away and swat the card away. You don't need to squeeze it or anything; just have a hand behind it to keep it from jumping or turning away. It will take a few tries to get his mouth open. Apply enough pressure for the frog to open its mouth but be gentle (unfortunately, it's hard to describe but easier to do). Have the worm ready in the other hand and right by the pac's mouth. When he opens his mouth, quickly insert part of the worm. You don't have to get the whole thing in there. He might try to spit it out, but the majority of the time once part of the food is in the pacman's mouth the will swallow it. It's not as complicated as it sounds, but it will take a few tries. Good luck and speedy recovery!