Intense love for Amos and Martha Halftrack. Shown most notably by Bryant Hollifield. One major symptom of Halftrack Fever is going crazy when Marty is seen in a bathrobe or when Amos wears his uniform. This is an intense disease. The only way it can be cured is loving them even more.
Marty: Have a nice day, dear. Hope you don't get Halftrack Fever!
Amos: Oh, put your robe on. I've already got Halftrack Fever.
Marty: (kisses Amos) I know. You've had it for 53 years. There's something about me you love.
Bryant: Its the robe. He loves it when you wear that thing! Even I do. See, there's magic in that thing.
Amos: Yes, you definitely have Halftrack Fever. You can't get enough of Grandma Marty in that robe. Or me in my army suit here. (he leaves)
Bryant: Hey, you want to get all cuddly? This Halftrack Fever is really working now.
Marty: Sure! We'll cuddle all day, honey. Amos is completely gone now. (she kisses Bryant) There's just something about me and you that I love. And its not just the robe. Its the Halftrack Fever. Gooey, sweet, cuddly. You rock!