Guadalupe-Reyes (wa•tha•LOO•peh•REH•jezz) is the period between December the 12th and January the 6th (both Catholic festivities). The first is Día de la Virgen de Guadalupe (Day of the Virgin of Guadalupe) and the second is Día de Reyes (Day of the Three Kings or Magi). In Mexico, Día de la Virgen, like Thanksgiving in the US, marks the beginning of the Christmas season. Día de Reyes marks its end.
Since this period is not too long and has plenty of Posadas, office holliday parties and other celebrations, some people have come with the clever idea of a drinking marathon called El Guadalupe-Reyes. It can take plenty of forms but one of the main ingredients is the agreement with friends and buddies to have at least one beer or drink every day from the 12th of December till the 6th of January. A popular variation of the Guadalupe-Reyes is to attempt the Reyes-Guadalupe which implies instead drinking from January the 6th until December the 12th, hoping not to drop dead before.
Piter: ¿Qué pasión Jonás? ¿Ya sabes qué vas a hacer con tu aguinaldo?
Jonas: Simón, me lo voy a gastar intentando el Guadalupe Reyes. ¿Le entras?
Piter: Nelson, estoy por terminar el Reyes-Guadalupe y la cirroris me esta acabando.
Peter: Wassup Jona. What are you going to do with your year-end bonus?
Jona: I will attempt the Guadalupe-Reyes marathon. Wanna join?
Peter: No way Jose, I am about to finish the Reyes-Guadalupe and am out of the door with a bad ass chronic cirrhosis.