1). A euphemism for life being unfair or difficult. A play on "If life gives you lemons, make lemonade" except with dicks.
2). A bad custom order at a diner.
1). Guy 1: Man, when Life gives you lemons, I guess you have to make lemonade.
Guy 2: Yeah, and if life gives you boners, make a boner salad!
Guy 1: What the hell are you talking about?
Guy 2: Uhh...
2). "I thought the waitress would have laughed when I ordered the boner salad. At least I know I'm never going back to that restaurant again.