Resting Dick Angle or RDA is the angle of a persons penis when in the flaccid state.
RDA is measured by first getting an errection and using a ruler and a sharpie to draw a line straight down the top of the penis. Then in the flaccid state a protractor is layed on top of the penis, positioned straight out from the hips. If the line drawn on the penis is striaght out at the 90 degree and that individual has 0 degrees of RDA. RDA angles is negative degrees if it's to the left of 90 degrees and positive if to the right of 90 degrees
Dude: Bro what's your Resting Dick Angle at today?
Bro: It's a little to the left dude... My RDA is - 3 degrees today!