We don't have synonyms for jam out yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are lam out and jam nut.
(v) :
(intransitive, informal) To experience enjoyment to the full, usually through music, relaxation, or spending time with others; to play music, especially in informal bands and featuring improvisation.
(v) :
(intransitive, informal) To experience enjoyment to the full, usually through music, relaxation, or spending time with others; to play music, especially in informal bands and featuring improvisation.