You aren't sure why, but you feel a strong urge to quack like a duck. So you do. Not just once, like six or seven times. You really get into it, you even squat down and pretend to waddle around a bit.
If the tower noticed your performance, it gave no sign. But still, you're pretty sure that you made the right choice. With that out of your system, you feel a lot more prepared to step inside.