10:15PM - Coffee as an Aid to Worship
This is a picture of Rupert Charkham, vicar of Holy Trinity Church, Cambridge: 
(HT: Radagast, who is considering visiting there.)
Notice particularly the poster in the background, and the reference to coffee as an aid to meditation. A lot of trendite churches now allow you to consume coffee during the service, and some even call themselves "Cafe church". In fact, I personally feel I can worship the Lord better with a cup of coffee in my hands.
Problem is, this is idolatory:
Question 51: What is forbidden in the second commandment?
Answer: The second commandment forbiddeth the worshipping of God by images, or any other way not appointed in his Word. (Westminster Shorter Catechism)
The Reformed perspective emphasises the centrality of the Word. Since the gospel addresses our intellect first (and then our emotions and our will), and since we worship through faith, worship props are unbiblical.
The confessions consider the second commandment to cover how we worship, whereas the first commandment addresses whom we worship. While the Reformers would have had images in mind particularly, coffee is presumably also excluded as an aid to worship.
Question 98: But may not images be tolerated in the churches, as books to the laity?
Answer: No: for we must not pretend to be wiser than God, who will have his people taught, not by dumb images, but by the lively preaching of his Word. (Heidelberg Catechism)
(UPDATE: Jaimie has written a good response to this.)