Center letter: b
Outer letter: g i n o t u
Answers (40):
  buttoning
  unbuttoning
  bigot
  binging
  bingo
  binning
  biotin
  biting
  bobbin
  bobbing
  bogging
  boing
  bonbon
  bong
  bongo
  boning
  bonito
  bonobo
  boob
  booboo
  booing
  boon
  boot
  booting
  bout
  bugging
  bung
  bunion
  bunt
  bunting
  butt
  butting
  button
  gibbon
  gibing
  noob
  nubbin
  obit
  tubing
  unbutton