Lindsay's going to jail! A probation violation hearing yesterday, she was sentenced to 90 days in the slammer. But the even juicier story is what she wrote on her fingernail for the hearing: "F*** U" (Gawker proves it's not a photoshopped pic). A secret message to the court? Classy, Lindsay.

Lindsay violated probation by failing to attend her alcohol ed classes based on the schedule set by the judge. She reportedly burst into tears at the announcement

But according to TMZ, Lilo will probably be able to pull the Paris Hilton express route behind bars: "Sheriff's spokesperson Steve Whitmore just explained ... generally, a female inmate in  Lindsay's situation only serves 25% of their sentence ... which means LiLo will most likely spend around 23 days behind bars."

Lindsay must surrender July 20.

Wow! Were you expecting her jail sentence? What do you think about her manicure message?