Yes, when someone is complaining about something they have to do anyways or when someone did a thing that ended with not very happy consequences... they have to SUCK IT UP ... deal with it, stop with the "crying" and start moving ... =)

The urban dictionary defines this term as "To endure a period of mental, physical, or emotional hardship with no complaining." In other words, if your friend is always whining about how he has to study for his classes, you could say, "Suck it up!" It usually would be used in the case of someone who is complaining about something that is really inconsequential compared with other people's problems. A phrase with the same usage is, "Tough it out!" This means to keep going through the adversity even though it is difficult.