[loungitude]

This is simple. Girls dot their I’s with little hearts or smiley faces and boys don’t.
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http://www.nytimes.com/1993/07/28/us/judge-s-optimistic-signature-on-a-grim-faced-death-row.html

[Fzob]

Charles J. Hearn, a Texas state judge, has been putting a happy face on his signature for years.

I guess it takes all kinds.

[expat1000]

I have a weird friend who used a vaguely similar doodle as his passport signature - I guess as sort of a libertarian protest gesture.

The thing is though, he travels a lot world wide - mostly in Asia, and while he was never actually denied entry anywhere, he got hassled about it so much he eventually returned to a normal signature.