From the Bio of Chong:
True to his comedy image, Tommy and his family ran Nice Dreams Enterprises, an internet company that sells marijuana bongs and pipes. He was arrested in 2003 on federal drug paraphernalia charges and sentenced in September of that year. He will spend 9 months in jail and pay around $120,000 in fines.
The only person of the 55 arrested during the US Drug Enforcement Administration's "Operation Pipe Dreams" to serve time in prison.