Samantha Ronson, the angrier and slightly muckier looking sister of Mark, was busted whilst driving home after a trip to Vegas. The news is currently being angled around the fact that she was pulled over by cops at 10.30am, like she must've been on some mentalist all night bender. We suspect she had actually got pissed*, been to sleep, woke up with a furrier tongue than her Lohan days, had a coffee and thought she'd be alright. Obv that doesn't make it any better, but it's an all too easy mistake to make; public service announcement coming up - know your limits, people - especially you celeb folk who seem to have never heard of the mini cab invention (in all fairness, Vegas to LA is a five hour trip).

TMZ.com reports that Ronson was arrested and charged with a DUI yesterday after a DJ gig in Vegas. It's claimed she was was pulled over for speeding in her black Porsche outside of Baker (which, TRUFAX, has the world's largest thermometer!) at approximately 10:30 am.

After messing up her sobriety test, it's alleged that she refused a breathalyzer test so was taken to the police station where it was determined that she was over the legal limit and thus was arrested. Still, at least she'd not been down on Lohan the night before or else the result would've been through the roof - boom boom.

Hope she at least got to enjoy that therometer upon her release, it's almost as interesting as the world's largest ball of twine in Kansas.

*Pissed in the English sense, although she was probably also pissed in the US sense because she always looks cross.