This has a double meaning depending on how big of a douche bag you really are. The first meaning is, the point at which you decide to unleash the beast as opposed to keeping it caged. This is done without knowing what your date's reaction will be. The second meaning is, when confronted with the possibility of becoming insta-dad, due to lack of trust or your bad luck, close to copulation due to the fact that your retarded ass forgot a rubber.
Dibble: Hey what do you think of my little pee-pee?
Jen: Oh my God its tiny but you know what they say "When in doubt pull it out".
Dibble: I'm gonna jizz but I don't want to contaminate the world with my seed!
Tamara: Well when in doubt pull it out i guess?