[arthurus]

If you scoff at my food you will be asked to leave. Scoff is a real legitimate word in real dictionaries. Scarf as a verb is an old commonly used but not entirely respectable word.

[Liz]

Scarf is something you wear around your neck on a cold inter day.

[justlurking]

If the two of you would quit arguing and look at a dictionary, scoff and scarf have both been used to mean "eat quickly":

http://www.dictionary.com/browse/scarf

http://www.dictionary.com/browse/scoff

If you follow the derivation, "scoff" was also a noun for "food" or "grub".

And a footnote offers an explanation for the mutation to "scarf":

1955-60, Americanism; variant of "scoff", with r inserted probably through r-dialect speakers' mistaking the underlying vowel as an r-less ar

[9422WMR]

I scoff at your desire to scarf the entire buffet. /S