the almost instant denial of responsibility you may hear from a past or present sexual partner after informing him/her that you just tested positive for a sexually transmitted infection.
The exchlamatory no does not necessarily take the form of a "no;" the only essential element is a denial. Responses such as "I just got tested a month/two weeks/a day ago and got a clean bill of health," "You're lying!" or "I don't have it" also qualify. The term is derived from the words "chlamydia" and "exclamatory."