The best replacement for boo is boom.

The best alternatives to boo are rated as following:
★★★★★  boom
★★★★  beau
★★  bowser
★★  jif
★★  boom game
★★  boom spongebob
★★  agnes
★  boo
★  ironpython
★  luigi
★  not to boo
★  bae
★  la chat
★  weeping angel
★  boom spongebob games
★  cake boss
★  cake boss family feud
★  khia
  kardashians
  bot
  hiss
  dnc
  boom games
  mr winkle

Your alternative for boo is not listed? Suggest!
Speaking about boo, one probably shouldn't forget about bph.

Other search terms related to boo and their ratings are:
★★★★★ bph
★★★★ alicia keys and usher
★★★ dr drew
★★ my
★ brew
★ usher and alicia keys
You have in mind a companion for boo and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of boo in all years. Click on graph for more.
boo
boom
beau