Shell cannot parse command values containing '!' exclaimation points

[pfdemo] pfdemo $ echo sdfdf!
sdfdf !
[pfdemo] pfdemo $ echo sdfdf!sdf
***ERROR*** Exception encountered: !sdf: event not found (type "set VERBOSE true" to enable stack traces)
[pfdemo] pfdemo $ 
[pfdemo] pfdemo $ echo 'asdf!asdf`
***ERROR*** Exception encountered: !asdf`: event not found (type "set VERBOSE true" to enable stack traces)
[pfdemo] pfdemo $