1.To have to suck it up and deal with a situation.
2. Another way, if used in the context "Lick my middle finger" can be another way to say "fuck you" in a less In-your-Face fashionisto.
Boyfriend: Hey, Tim my moms coming over for brunch!
Tim: But...ugh..babe, i love you, but your mom...are you serious? c'mon, you kidding me? why are you letting that woman in our house?
Boyfriend: Look, sometimes you just need to lick the middle finger and suck it up, she's your mother in law.