San Cristóbal Totonicapán is a municipality in the Totonicapán department of Guatemala.
Map of San Crist%C3%B3bal Totonicap%C3%A1n, Guatemala
In the second week in December they have a festival called "Festival de Guadalupe" where people paint their whole bodies with body paint to become diablos. They then walk through the main street and are likely to smear some paint on you.
References
San Cristóbal Totonicapán Wikipedia(Text) CC BY-SA