Gunk will get inside your keyboard no matter what, but hmm, crumbs. The G55/G75 keys fit pretty tightly, so that has to be some hardcore eating....
Anyway, try blowing with a can of compressed air. If something is REALLY stuck, you can either try to very carefully slip something thin under the key(s) involved and try to push it to a location where it can be brushed off. Sometimes turning your laptop upside down and patting the back VERY LIGHTLY will help dislodge the gunk, too, although this method is really really REALLY not recommended unless you're truly desperate. Not sure how a keyboard vacuum cleaner would work with this kind of keyboard, but you can probably use them in combination with compressed air and thin utensils to good effect.
