Not bad - it's a decent concept and a simple no-frills platformer. It's still a bit glitchy, though: if you attach a plunger when you're right next to the pipe, Gary becomes permanently stuck in place (you can't pick up the plunger, jump, or move - you have to restart the level). On a trivial note, some of the formatting of the writing is a little off (for example, in the instructions, the words don't line up with the images when describing how to plug the pipes).
One suggestion: right now, if you jump and try to attach a plunger, it simply shoots straight down and disappears. I'm not sure if this was intentional, but perhaps you could make Gary a little more intelligent in that regard? :)
Cracked FTW.