Conrad Hilton, the youngest brother of Paris, is currently locked up in a Los Angeles juvenile hall!

The 18-year-old was arrested after he tested positive for marijuana, which violates his probation… from a past marijuana arrest.

Hilton will be held behind bars until a trial can take place in front of a judge.

What’s unfortunate for the teenage heir is that it is Friday and the judge won’t be in until Monday!

A rep for Hilton has yet to make a statement.

Well like brother, like sister.