tom o bedlam

from The Collaborative International Dictionary of English v.0.48

Tom o' Bedlam \Tom o' Bed"lam\
   Formerly, a wandering mendicant discharged as incurable from
   Bethlehem Hospital, England; hence, a wandering mendicant,
   either mad or feigning to be so; a madman; a bedlamite.
   [Webster 1913 Suppl.]