Who's Trying to 'Clean up' Amsterdam?

Today, as I was riding my bike down Utrechtsestraat in the eastern canal belt area, I saw one of those sights that just makes me laugh, shake my head and say to myself, "Only in Amsterdam." As you can see in these photos, someone sought to stop passers-by in their tracks by turning the fountain at Frederiksplein into a big bubbly spectacle. Not sure who the squeaky-clean culprit is, but his or her sudsy stunt seemed to put smiles on kids' faces and give locals and tourists alike a great photo opp.