Flat for the most part, although even at room temperature and open to atmosphere, you will get a bit of head. Beer engines were developed to maximize this on the draw, as well as sucking the beer out of the keg.
Remember one unassailable statistic, as explained by the late, great George Carlin: "Just think of how stupid the average person is, and then realize half of them are even stupider!"
"I would like to die on Mars, just not on impact." Elon Musk