http://www.google.com/patents?id=T2QKAAAAEBAJ&dq=%22swing+on+a+swing%22
And it issued.
"Obvious" is a bad word. Well, there were billable hours burned in preparing it. They have hired an awful lot of new examiners, and my last few applications took quite a bit of back-and-forth before issuing -but it looks like this guy won the lottery, and managed to get an examiner who never used a swing as a child.
Glad I retired.