Police arrested Paris Hilton on cocaine possession charges after she and boyfriend Cy Waits were pulled over late night for leaving a Cheech & Chong-style trail of marijuana smoke from their vehicle. Yahoo News says:

The 29-year-old Hilton was in a car driven by a friend when it was stopped about 11:30 p.m. Friday after officers detected what they suspected to be marijuana smoke wafting from it.

During the stop, officers found what appeared to be a drug on Hilton and later tests showed that it was cocaine.

The socialite was booked into the Clark County Detention Center early Saturday [and] released before dawn on her own recognizance.

And her explanation for the night’s events? Airtight, of course! The coke the cops found in her purse was not hers — it was somebody else’s. And possibly a setup. TMZ says:

Hilton now says one of her friends recently borrowed the purse in question and “probably” put cocaine inside. Paris says she got the bag back but never checked the contents.

Paris is telling friends, “I had no idea the cocaine was there. I swear on my life. It could be a setup. Everyone knows how against cocaine I am.”

How come that explanation never works for any of the people I see on COPS? This is the third time she’s used that bullshit excuse (here on July 5th, and again on July 19th) and gotten away with it. The “I’m being framed” bit is a nice touch, though. Lindsay Lohan must have stepped in as acting consigliere.

In L.A. last week:

PHOTO SOURCE: Fame Pictures