Someone who rarely, if ever, leaves his or her house. In this person's mind, his or her house is so decked out that there is no reason to go anywhere else. Home gnomes are annoying because they never want to meet up with you when you're out, instead opting to invite you to their house and making you drive the whole distance to them every time.
Person A: Dude, let's hang out.
Person B: Sure. You wanna come over to my place?
Person A: How about we meet at the bar instead?
Person B: Nah, I really don't feel like going out. We could order some pizza here & I have a six-pack in my fridge.
Person A: Bitch, you're such a friggin' home gnome.