A student at Centennial High School in Bakersfield, California reportedly handed out the buns to classmates who were picking on her on Tuesday.
Another student contacted a local TV station and said the girl had put pubic hair, semen, out of date food and pills into the mixture.
When some students asked her why the cakes tasted so bad, she told them they were made with bodily fluids.
But police investigating the incident say it was nothing more than a "high school prank" - and that the cakes were made with mayonnaise, barbecue sauce and soy sauce.
Officers said suspect and witness statements indicated there were no bodily fluids or poisonous substances baked into the cakes.
Most students thought the cakes tasted so bad they didn't eat them, but one classmate ate a full cupcake and stayed home the next day with digestive problems.
Students were notified by school officials that a new policy banning outside food being brought into the school took effect on Friday.
The cupcakes have since been destroyed and no arrests have been made.