If I'm asked for an estimate to do X and I say I can deliver in three weeks, and my boss says customer needs it for golive in three days, I'll try to find some way of making that work. Perhaps they can live without a full solution for the first few weeks, instead requiring only a subset of the requirements in that period. Or, if I insist it just cannot be done, I'll tell the boss who'll try to push back golive if it's important enough.

There needs to be respect for each other and the project though.