Gavin,
to slosh....to cause (a liquid) to move in a noisy or messy way
The child sloshed the water in the tub.
to slosh down....to drink quickly and perhaps noisily
I ate like a pig at Goods Restaurant and then sloshed down a beer or two at Lloyds Bar
Upon their return to the car Lee lit up a Camel and sloshed down a Coke.