When they called the city's 311 hotline to complain about Sunday's Nike marathon, they were incorrectly directed to a phone sex line.
City officials now say they were given the wrong number and are investigating how the mix-up occurred.
The phone sex number and marathon number differed only in their prefix: 800 versus 866.
311 Director Nancy Alfaro says the wrong number was given out for about a half hour before city officials were alerted. It's not clear how many people were misdirected.
The San Francisco Chronicle reports people were complaining about noise from the marathon's festivities that began around 5:30 a.m.
An email to Nike was not immediately returned.