It's one of those behaviors that some find very useful. And it's not that difficult to teachFirst, observe your bird; learn to anticipate when it is about to go.  Typically, because of their fast metabolism, birds go about 30 minutes after eating.  They also have a tendency to go before taking off.  And when they awaken in the morning, since they don’t go while asleep.  Get to know your bird’s rhythms and habits and you can learn to anticipate a potty break.  There are certain physical behaviors that tip this off, like puffing the feathers, quivering, pumping or wiggling its tail.  Once you’re able to recognize it, just as it is about to go, you use a consistent verbal command, like “go potty,” “kerplop,” “let ‘er rip,” or “bombs away.”

The bird becomes used to associating those words with the act of going.  It will soon develop a conditioned response to the command and be stimulated to go when you say it, provided, of course, that the bird is ready to go.  So, when your bird hasn’t gone in a while and you’d like to perform a pre-emptive potty break, to save the carpet, you hold it over a safe place, a trash can, it’s cage, a potted plant, then say the secret word and bombs away. 

You can’t make it go when it doesn’t have to go and you can’t stop it from going when it really needs to go, so be sensitive to its needs.  But your bird will learn to hold it as long is it is not uncomfortable to do so.  And it does enable you to stimulate it on command, if the general timing is right.