Poor guy. Your friend needs to be doing daily 100% water changes with dechlorinator in a container that tiny--from the picture it looks to be a gallon or less. Fish constantly excrete ammonia through their gills, kind of like urine. In a closed system where there's nothing to consume or remove the ammonia, the toxicity level rises extremely quickly--to the point that it burns the fish. It is very inhumane to keep a fish this way. Imagine having to breathe in, drink in, and lay in pee all day. Not nice.
I highly suggest getting a temporary container to keep him in that is long and shallow. You can get a 4 gallon rubbermaid/sterilite plastic storage bin from walmart or target for about $3 and fill it up halfway. This will mean the fish will not have to strain to reach the surface in order to breathe and he will still have plenty of swimming space. Your friend also needs to get a heater--bettas are tropical fish and despite what you hear in the pet store, heaters are not optional. Keeping them at low temperatures can have serious consequences. I only recommend heaters that have an adjustable temperature dial like this one: http://www.fosterandsmithaquatics.co...8&pcatid=11368
--but you will likely need a larger container to use one of these.