From Twitter by Doc Norton (@DocOnDev)
A: How long will it take to build this simple feature?
B: Well, how should this part work?
A: We don't know yet.
B: And in this situation...?
A: We don't know yet.
B: And Here?
A: We don't know yet.
...
A: So, how long?
B: We don't know yet.
A: I thought you were professionals.