not likely!

not likely

Definitely not. Used to emphatically indicate that one completely refuses or disagrees. A: "Are you going to Jen's party this weekend?" B: "Not likely! She's been a total jerk to me lately." Help him, after all the trouble he's given me? Ha, not likely!
See also: likely, not
Farlex Dictionary of Idioms.

not likely!

certainly not; I refuse. informal
See also: not
Farlex Partner Idioms Dictionary

not (bloodytaboo, etc.) ˈlikely!

(spoken, especially British English) used to disagree strongly with a statement or a suggestion: Sign a blank cheque for you? Not bloody likely!
See also: not
Farlex Partner Idioms Dictionary
See also:
  • definitely
  • definitely not
  • Definitely not!
  • aint
  • ain't
  • (I) hope not
  • hope not
  • not (one's) long suit
  • not for a second
  • not for a moment