Fishers have reported successfully using Velveeta cheese as fishing bait when it's placed on a size 16 or 18 treble hook. People report the rolling the cheese into balls that resemble fish eggs make catfish more likely to bite.
Velveeta loses its color and turns white once it's placed it water, which makes it look even more like an egg. Catfish eat a wide range of food, and their opportunistic nature means that fishers have successfully used a wide range of bait over the years. Whether Velveeta cheese has intrinsic properties than make it an especially compelling bait is not well established, but its low price might make it worth trying.