Regina, Saskatchewan; Canada
This is very very bad grammar.
It is correct to say "Am I not?" Or to avoid repeating "am" in a saying such as "I am cunning, am I not?" one may say:
"Am I not cunning?"
"I am cunning?"
"do you know I am cunning?"
And for you that appreciate English of all ages:
Nam I cunning?
(Nam = ne "not" + am, as in never = ne + ever)
Much better than the bad grammar of "aren't I?"