On a moonlit night last March, when Roxanna Cohen drove into her driveway, she was astonished to see a flock of plastic pink flamingos planted in her garden. A white board amid the slender birds read, "You've been flamingoed by S.T.A.R.F."The perpetrators of the practical joke were Emily Lohmeyer and Paige Prentice, both 17-year-old seniors at Nevada Union High School. The two girls are raising money to visit Spain after graduation to learn more about the culture and language. Incidentally, S.T.A.R.F. stands for students traveling abroad and raising funds.The person who is "flamingoed" can call a phone number to find …