If you're on Facebook you can hardly miss someone posting the the photos of the mysterious pink mechanically separated meat. If you want all the fun without all the grossness, check out Gardein's Crispy tenders. It's been awhile since I've had an actual McNugget, but these make a pretty good substitute. Mmm bbq sauce...
I'm working my way through trying all the Gardein varieties. I've found them frequently at regular grocery stores, but you can find them at Whole Foods as well. There are some varieties in the fridge section and some in the freezer. Also may randomly appear in the fresh fruit and veggie section.