A puke-a-hontas is a girl, typically with long brown or black hair, who gets drunk and projectile vomits all over your car, apartment, house, etc - anywhere but in a toilet. This term can also refer to a guy who gets drunk and starts acting girly and pukes all over. Generally in the latter case the male is crying.
person 1: How was your date last night?
person 2: It was going great at first. We had dinner and drinks, then made it back to my place. We're at my front door making out and we take two steps inside when puke-a-hontas vomited all over my hallway.
It's a percentage of positive-ness when you are not quite 100% sure but you are about 95-99% sure about something. Much like the variance in birth control effectiveness, depending on the type of person saying they are “birthcontrolpositive”, they’re percentage can fluctuate as low as 80% if they use it improperly. However, when used in combination of another friend who is also birthcontrolpositive, it can be 99.99% accurate.
person 1: Are you sure that it's supposed to rain today?
person 2: I am birth control positive that the weather man said to expect rain all weekend.