What does "When a girl steals your hat and wears it.>>>" mean?

[Katherine Roullier]

Specifically the greater than symbols.

[Posydon]

She's a dirty thief

[Joe]

shes to cheap to buy her own hat

[Andrew]

It mean something along the lines of 'there is nothing better then when a girl steals your hat and wears it' (greater than symbol = greater than anything else). I bet you saw that as a tweet on Twitter. I see some that are as simple as 'ice cream>' (meaning ice cream is better than anything else). The extra greater than symbols ('>>>' vs '>') are just for emphasis.

It is thought of as cute when girls take a guys hat/jacket and wears it because it is a sign of love and appreciation.