Its a plate of food. Something I sometimes provide whether asked or not, when I go to friends place or party (including kid's parties) to contribute to the occasion and the effort they have made. Its interesting to me that this topic has generated so much feeling. Perhaps there are some cultural norms I haven't been exposed to .
Just because it isn't the way some of you would hold a party, doesn't mean it is wrong or rude IMO, it is just different.