When you're working in the food service industry, there's not a whole lot to be excited about—unless you're Frank, Plumpy's resident overachiever. "Frank was younger than me, so he still had a little enthusiasm for his work," Sam explains. "Brooke, Ramon, and I had all started a pool on how long it would take for this place to suck the life out of him" (1.17). This makes it sound like he's the butt of the rest of the fry crew's jokes, but really, he's that friend the rest of the gang just delights in annoying.
Frank's main deal is that he's way too nervous and eager to please, and that's not just while working behind the counter at the restaurant. After Michael attacks Sam and the group arrives safely at Sam's apartment, Frank picks at his shirt and tries to convince Sam to go to the police and say he's been assaulted. Somehow, the logic of telling the cops about the guy who ripped off Frank's bumper doesn't add up for him, but he keeps pushing the issue. Not only that, but "If he kept it up, he wouldn't have any shirt left" (4.19). Call him Nervous Nelly.
Later, Frank's eagerness makes another appearance when he brings the bowling bag over to Sam's and tries to sell him and Ramon on the idea of carrying Brooke's severed head around in it. Again, he doesn't seem to understand that carrying a bowling bag around at any location other than a bowling alley is super weird. Still, Sam decides to give him the benefit of the doubt and use his idea. "Honestly, even if it didn't work, I couldn't have told Frank no right then," Sam states. "It seems to mean so much to him that he help in some way" (9.77). Nice kid, this Frank is.
Frank may be kind of a loser, but things turn out all right for him in the end. After Sam inherits Douglas's estate, he invites Frank to quit working at Plumpy's and join him as his personal assistant. On the way to Sam's apartment to close the deal, Frank "babbled at me the whole time. I only half listened, letting his voice roll over me, happy to see him again. Happy that at least Frank had made it through this whole mess unscathed" (31.12). Indeed. If someone is going to get out of this situation without a scratch on him, it might as well be Frank.