The Igs are real, they aren't considered a joke like the razzies. The recipients receive their prizes from actual Nobel prize winners. Quote from their website (http://improbable.com/ig/) 'The Ig Nobel Prizes honor achievements that first make people laugh, and then make them think. The prizes are intended to celebrate the unusual, honor the imaginative Ã¢â‚¬â€ and spur people's interest in science, medicine, and technology'
Sheldon has often hinted at his desire to be a recipient of the Nobel Prize. I would love to see an episode showing Sheldons reaction if he was instead a finalist for an IgNobel prize. Perhaps for a dissertation he wrote as a joke about he origins of the word 'Bazinga!'.