AU REVOIR, CRAZY EUROPEAN CHICK by Joe Schreiber

Perry is finishing his senior year of high school near New York City.  His family has hosted a foreign exchange student from Lithuania this school year, and Perry's mother is making him take Gobi (the Lithuanian student) to prom.  When Gobi decides to attend prom in a traditional Lithuanian costume, Perry is ready for a night of ridicule and humiliation.  However, the night turns out nothing like he planned.  Gobi is not really an 18-year-old exchange student; she is really a trained assassin from Lithuania and forces Perry to drive into Manhattan so she can complete the killings she has been planning for the last 9 months.

This is one of the few books that I've read in one sitting.  It is predictable and unrealistic, but great fun.  The tone is one of light-hearted escapism--even with the violence and serious motivations of Gobi.