I'll give the OP the benefit of the doubt and assume he bought the ticket because there was a company in attendance that he/she was interested in or for the greater networking opportunity. But what a soul-sucking experience these "job fairs" can be! I went to one and that was enough. Usually the only winner is the guy who put the thing together. I would suggest that something like WAI or OBAP are far more fun and more useful because they are more like a convention where you have a greater chance to enjoy yourself, break the ice and interact with a recruiter in a meaningful way. At these one-day cattle calls you mainly just stand around and awkwardly swap small talk and business cards with a bunch of guys who all look the same as you until you get your 5-10 minutes of face time with a recruiter.

I don't condone the idea...but if you DO call in sick, for the love of GAWD, do NOT jumpseat or non-rev to the job fair!