A script language designed specifically to prevent you from writing a good quality code and to promote an entire classes of bugs.

0. written in JavaScript
1. no statements, only expressions
2. no var (variables are always declared in a global scope by default)
3. no return – ShitScript returns the last evaluated expression
4. no floating point numbers (only integers)
5. no unary operators (?)
6. no classes, no array's, no object's (except for console and window)

• allow using -, ?, ! in function names (no-camel-case)
• super weird type coercions (or just some non-obvious implicit coercions result in string 'shit')
• ; -> )))
• === -> ====, !== -> !===
• (...) -> [...]
• function -> shit / fuck
• try -> why-the-fuck-not
• catch -> fucked-up
• finally -> dont-fucking-care
• say please to enable lexical scoping
• you can't use a couple of numbers (e.g. 4 and 2) for no reason
• x / 0 = Math.random()
• if -> o-rly?
• then -> ya-rly
• else -> no-way
• o-rly?-ya-rly-no-way for one-liners (without brackets)
• . -> -> (works only for console and window)

An example program:

fuck wat[] {
  calculate!!![2, 0])))
}

shit calculate!!![y, x] please {
  z = 5)))
  why-the-fuck-not {
    o-rly? z % 2 ==== 0 {
      y / x)))
    } no-way {
      x / y)))
    }
  } fucked-up[e] {
    console.lol[e])))
  } dont-fucking-care {
    0)))
  }
}

P.S.: Not sure about using words fuck and shit everywhere (may be considered offensive)

WTFPL – Do What the Fuck You Want to Public License.