There's a discussion of this in The Straight Dope Tells All. The leading theories are:New York Times, you seem to need a little help, so... let me Google that for you.
- The melting ice acts as a slow, continuous flush
- Ice cools the air around the urinal. Cool air sinks, which serves to contain the smell
- Cold discourages drain flies
- Fun to melt, helps users aim better, compensates for poor male sanitary habits
June 20, 2010
In this (possibly useful) article about (relatively) cheap but (somehow) stylish hotels in New York City. I don't go — no pun intended — in the bathrooms where one finds urinals, but if I were writing that article, I would at the very least Google the phrase "ice in urinals" before leaving it in an article. I would know that some readers would Google "ice in urinals" and I wouldn't want to be embarrassed if the answer was something it would be embarrassing not to know. And once I'd done that, I'd know the answer, because "ice in urinals" gets "about 231,000 results" in Google, beginning with "Why Ice in the Urinals?" in AskMetafilter. You see this right away: