Not to be confused with wtf
? - the question mark character "?" either:
  1. alone (not part of a sentence) or
  2. at the end of a sentence.
"?" usually denotes wonder, confusion, or curiosity, examples: 
1:
∧＿∧
（゜Д゜　）   ?

2:
∧＿∧
（゜Д゜　）   Seriously?