When you need something off of a parent or anyone in the same house/flat as you, you shout 3 times, starting quietly and gradually increasing into a scream on the 3rd shout.
'ahh i could really do with a drink right now but i cant be asked to get out of bed, lets see if mums around'
'mmmmm no reply'
'hmm still no reply'
thus demonstrating the perfect 'the 3 shout'