(cat-whistle?)
Pussycat, Pussycat, where have you been?
"I've been to London to visit the Queen."
Pussycat, Pussycat, what did you there?
"I frightened a little mouse under the chair."
(note: this particular whistle has no specific meaning other than just being a whistle for the sake of it)
If you find this post or its associations offensive, then the whistle has been effective.