That is probably referencing that you bought something in the British pound that was 50 pounds, but in US dollars it is was $101.37 (as of 12/7/2007)
http://www.google.com/search?q=50+gbp+in+usd
If you buy alot of things online over in Europe you could have all sorts of charges like that on your statements. With the declining dollar you have to be careful about what something really costs.

