Google Maps relies on a feature called Map Maker that lets users around the world update it. This helps the company use local knowledge to keep up with ever-changing infrastructure. Those changes are theoretically reviewed by other users and a moderation team.
But it seems as though Google isn't keeping a super close eye on all of the changes -- as evidenced by another message found nearby.
It's unclear how long the images have been up, but a Google spokesperson said the company is working to remove them.
"We’re sorry for this inappropriate user-created content; we’re working to remove it quickly," Google's Mara Harris said in an e-mailed statement. "We also learn from these issues, and we’re constantly improving how we detect, prevent and handle bad edits." The vast majority of users who edit Google Maps provide "great contributions," Harris said.
This isn't the first time Google Maps has been used by pranksters: Just last week, someone added a listing for "Edwards Snow Den" in the White House -- an apparent reference to former National Security Agency contractor Edward Snowden, who pulled the curtain back on government surveillance programs.
And one Massachusetts man has been trying to use Google Maps as part of his quest to get a local island named after the rapper Busta Rhymes for years. (It currently is labeled as such by the service.)
But the openness of Google Maps can also have more serious consequences. Security researcher Bryan Seely was able to intercept and record calls meant for the FBI and Secret Service merely by changing the number listed for some office locations in the product, Valley Wag reported last year.
Correction: An earlier version of this post misspelled security researcher Bryan Seely's name as Brian. We regret the error.