What should I do while my friend is singing/monologuing?
There sure is. When you're not singing/monologuing you should roll around on the floor, screaming nonsense phrases such as "Bananas! Hideous bananas!" and "Purple were their eyes! Purple, I tell you!". You may also consider making rude gestures towards those who are watching, and perhaps make rude and/or suggestive comments about their clothing, especially their trousers. Hope this helped