The dummy won't feel anything if he's submerged in corn. Besides, the "dummy" in this photo is attached by a harness so he can be rescued right before the corn takes him under.
This scene is a mock rescue training for firefighters and students that occurred a while back. It was part of a program put on by Steve Wettschuranck and the Purdue University Extension safety effort, headed by Bill Field.
Steve has trained so many fire departments both in and outside of Indiana that there aren't any trainings scheduled this fall. That's not because the topic is no longer important, it's because so many volunteer fire departments and rescue units that want the training have already received it.
Related: Use Caution Around Grain Bins
Part of the training program centers on convincing people how quickly someone can be sucked into flowing grain. It happens most often when someone makes the sometimes fatal error of climbing into a grain bin alone, without a harness, to unclog a spoiled mass of grain that is blocking the unloading auger.
As soon as the clog is freed, and grain starts flowing again, the person is at risk for being sucked into the pile. You can be totally submerged in about a minute. Field has explained this to many audiences in the past.
Part of the reason for the demonstration is that spoiled grain is visible inside the bin. Note the pieces of stalk and other debris in the corn. If this were a large bin, those materials and fines - pieces of small corn and other debris - tend to settle in the center of the bin.
Unless you core the bin and pull out one or more truckloads of that material, it can set up a place for grain to mold and insects to work, especially if the grain is not dried and aerated properly. Once that happens, blocks of spoiled grain develop. When they break free, plugging happens.
The message is simple: don't be dumb like a dummy. Keep grain in condition, and if you have issues, follow the proper safety protocols to stay out of trouble.