Nutella

Nutella is a chocolatey hazelnut spread that comes in a jar produced by Ferrero SpA, an Italian manufacturer of chocolate and other confectionery products. It is a soft chocolate spread made with hazelnuts, similar to Praline.

Popular in Europe and also in the United Kingdom, it is sold in jars that are designed to mimic drinking glasses with a tight-fitting plastic lid, such that once the product inside is finished what remains is a drinking glass. In the US, plastic jars with screw-on lids are instead sold.

Nutella and furry
Nutella has some popularity among furs for some reason, possibly going back as far as EuroHowl 1997. Nutella-covered dog biscuits were something of a running joke on alt.lifestyle.furry back in the late 1990's (the fact that chocolate is a bad idea for dogs notwithstanding).

The mystery behind this chocolate is more of a running gag since the joke occasionally appears during many different furry conventions. It is a mystery as to why this particular brand was chosen.

This is the source of Smrgol's yearly donation of six or eight jars of Nutella to charity auctions, including those of Anthrocon and Midwest FurFest.