A trio of Pennsylvania teenagers pleaded guilty this week to “icing” a birthday cake they gave to a high school classmate with human feces.

The three young women--Mayra Flores, 19; Ana Mireles, 18; and Sandra Ortiz, 18--copped to reckless endangerment and conspiracy charges stemming from the repulsive prank they pulled earlier this year. A fourth student, who is a minor, faces juvenile charges.

Flores, Mireles, and Ortiz were each sentenced Monday to 22 months probation and ordered to perform 200 hours of community service.

According to a criminal complaint, on March 23 the four pranksters gave the victim a cake for her birthday. While at Avon Grove High School, the quartet “kept trying to get her to eat the cake in front of them, until she finally ate a small piece,” a state trooper reported.

The victim brought the cake home, where her mother and the teen’s three juvenile siblings “all tried a piece of the cake.” However, “They all thought the cake tasted bad so they threw the rest of the cake out,” the complaint notes.

When the disposed cake “started to smell very bad,” the victim took it out of the garbage and brought it back to school to show to her teacher. During questioning by the school’s principal, Flores, Mireles, Ortiz, and the minor admitted “that they placed feces on the cake as a prank.”

A subsequent lab test revealed that the cake tested positive for the presence of E. coli, confirming the fact that “feces is present in the cake.”