These are some of my treasures, discovered while implementing a Python parser years ago.

First, the "surprising comma."

Codepad: http://codepad.org/JiFQi7vr

def f(**args, **kwargs):
 print args, kwargs

def args = 5, 7
f(42, *args,)

Technically only f(*args,) or f(**kwargs,) is needed to tickle this one.

Second, the "not knot."

Codepad: http://codepad.org/IA7k5jEg

x = True
y = False

print not x == y
print x == not y

Again, a smaller test case, like x == not y, will provoke it.