Come up with a name and description. The description can be funny or serious. Name has to be relevant too. A color for the effect would be nice too. Also, if it's funny, you can grab some effects from other games and kinda shorten it out.
Status: Jelloified
[excessively long] Description: Cave Johnson here. I've recently discovered some new tech after merging with the famous company you know as Jello. After experimenting with science I've recently discovered this can be used as a shield. It will encase you in Jello.
I've got some good news and bad news for it. The good news? The Jello is so resistant to other items you'll be protected for -2 turns.- The bad news? Well, since you can't really move in Jello, you're gonna be stuck in there until you get out. And you're probably trying to eat it, so you might get fat and slow yourself down. The stickiness is probably gross too, so there's that.
Cave Johnson, we're done here.
In short, Dig without the attack for 2 turns, speed debuff, and in a rare case grossed out effect.