In the United States Army, Physical Fitness tests are given every six months and soldiers must pass with a 60 in each of the three events adding up to a minimum passing grade of 180. A 181 is when a soldier gives the minimal effort due to extraneous circumstances to pass the Army Physical Fitness Test. So a 181 is an acceptable, yet less than enthusiastic effort in order to accomplish a goal.
Soldier 1: Oh man today is a 181 day.
Soldier 2: Definitely, I'm so goddamn hungover from penny beer night I can hardly stand up.
Jack: Man I really don't give two shits about this final exam.
Joe: Just make it 181 and call it a day.
The numerical representation for a ménage à trois between one woman and two men.
Dave: "Hey bud, she looks prettty wasted!"
Ty: "Ya, she does."
Dave: "Shes hot man, go in for the kill, we'll pull some 181."
Ty: "Ménage à trois?"
Dave: "Yeah, but if we pull a clash of swords, I'm out ASAP."
The (incorrect) metric conversion of the sexual position, the 69er, heard on a forgotten comedy show in the 90's and perpetuated by those who have repeated the joke and not checked a conversion calculator. 1 inch = 2.54 cm, answer should be 175.26.
Some credence should be given however for the homonym, "one ate one".
The number after 180 and before 182.
Teacher: What comes after 180?