We hope Osama "Sam" Lutfi has a good attorney or a lot of hard evidence of his latest allegation against Britney Spears, because it's a whopper. The shady, self-proclaimed former manager of the nouveau 'X Factor' judge just dropped a bombshell: He says drug-sniffing dogs found crystal meth at Spears' home.

For those of you who don't remember, Lutfi was lurking around Spears during her darkest time -- the head-shaving, 'Gimme More,' 'Blackout' era -- and has been trying repeatedly to sue the pants off of the starlet for years now. His latest defamation suit covers a slew of allegations, but this is the first filing in which he accuses Spears outright of drug use or possession. Additionally, Spears' legal team have previously gone after Lutfi himself for wrongful retention of drug test results. Yikes!

Lutfi's latest allegations are part of his same ongoing defamation suit against Spears and her family -- he claims that Spears, her mom, Lynne and her father, Jamie (who is now her conservator) said that Lutfi drugged Spears. Spears hasn't testified in the case because her conservatorship deems her unfit to do so -- and in his newest filings, Lutfi lists what he wants her to testify about later on. He specifically listed a 2007 incident in which he claims police "brought drug-sniffing dogs into her home ... and they found a cache of crystal methedrine, which was destroyed ... Britney should further testify that drug dogs found 'hot spots' of drug residue in the carpeting, where her young sons played during visits."

Since this is a defamation suit, it's interesting and pretty scary that Lutfi would launch allegations like these against Spears, because if they wind up being untrue, she and her conservators could clean him out in a defamation suit of their own. Lutfi also claimed that Spears told him her father -- the guy credited with saving her life and sanity -- is an "alcoholic racist." Right.

Lutfi's also been trying to use Spears' new job as an 'X Factor' judge -- and fan favorite -- as evidence that she's competent enough to stand trial in his suit. Additionally, his suit may also delay her wedding to fiancee and manager (actual manager, mind you) Jason Trawick, because Lutfi argues that if she's okay to get hitched, she's good to speak on the stand.

Watch the Britney Spears 'Piece of Me' Video