When your mom gives you an excessively long lecture about stuff you did wrong.
I left my bike out in the rain and had to come inside and listen to my mom give me a two hour momologue about how I need to learn the value of money.
When your mother or mother-in-law calls to talk about everything and nothing at the same time. You have no hope of ever contributing to said conversation, and this tends to last for hours at a time. Unless you can find a timely excuse to get off the phone, you "lose signal", you pass the phone off to someone else (also known as a dick move), or she runs out of things to say (ie, the end of the world) you are permanently glued to the phone.
Jimmy was waiting for his girlfriend to call and was unfortunate enough to walk into a momologue due to his lack of caller ID.
Larry had been subjegated to so many hours of momologue, that 6 days later his landlady discovered his emaciated body attached to a phone, with some faint chatter going on in the background.
"Dude, your mom needs friends or something, thats the 3rd party you've missed this month."
"Dude, I know! She momologued for so long, I took a nap, woke up, and she was still going on about Aunt Linda's dog!"