I just found (at a German delicatessen!) a very good dictionary of Costa Rican slang called A Lo Tico. (tico = costarricense) It was written by Alf A. Giebler Simonet (ISBN: 9977-12794-8, Grupo Deseños Impresos, SA). I paid C$2500 (about USD$5.00). It has 216 pages. In addition to slang, it discusses how Ticos abbreviate words (porfa = por favor, te =teléfono, re = reunión), common expressions (Más asustado que monja con atraso), how to give directions (in a country without street signs and house numbers), and makes other interesting observations. It's not as scholarly as the old standard Nuevo Diccionario de Costarriqueñismos by Miguel A. Quesada Pacheco, but it appears to me to be much more current. No, I have no idea how and where you can get a copy.