vulgar slang A derogatory exhortation to start acting in a more masculine manner; that is, to be more direct, aggressive, courageous, self-confident, and other such characteristics that are stereotypically considered to be masculine attributes. ("Pair" here refers to testicles, but the phrase can be said of or by both men and women.) You're never going to get the boss's respect if you keep kowtowing to him like that. You need to strap on a pair and show him that you deserve to be taken seriously! Janet, I know you're nervous about asking Tom out on a date, but just strap on a pair and give it a shot!