If you're really up for a gag, you should eat the entire plate of bread and drink the entire glass of wine...that would get everyone in a tizzy and probably get you kicked out promptly :)
Darn, so that means you could probably only eat all of the bread before they catch on and the elders circle you like piranhas :-(
Or, just bring your own wine =D And pull it out after eating the plate of bread!