She had never met the maintenance man who maintained the old clockwork dragon that served as their protector. She only heard him talking to it as she cleaned the area around the entrance. He spoke in a strange language, clicks and whirrs and high-pitched hums and whistling that she couldn't make heads or tails of.
So when she heard a two clear, distinct knocks on the thick wooden door that marked the resting place of the dragon, followed by a male voice saying "knock knock", well.
Was there anything else to do but reply "who's there?"
It took a moment, but the male responded. "Dishes," he said.
"Dishes who?"
"Dishes a very bad joke."
It had been ages since Toriel had heard a joke as bad as that- well, frankly, it had been ages since Toriel had heard a joke period, but that's beside the point- and so she had a full-on laughing fit, as if trying to catch up on all those years of silence she had brought upon herself.
It seemed the man on the other side of the door enjoyed her laughter, as he proceeded to tell her another joke every time her laughing fits threatened to end.
Finally, after a dozen jokes, Toriel thought of one herself and was finally coherent enough to say it. Before the maintenance man was able to, she knocked on the door.
"Who's there?"
"Old lady."
"Old lady who?"
"Oh, I did not know you could yodel!" she chortled, and he along with her.
"That was pretty good, lady. But I really gotta get going; my bro gets cranky if he doesn't get his bed time story."
"Ah, oh, of course," Toriel started, sad to lose her new friends. She tried a few times to say something, but nothing came out. It was pathetic- she, a former noblewoman, a queen even, unable to ask this man who had made her a little less lonely for a few minutes the simplest of things: to come back. He was the maintenance man, he'd be in the room again, but would he knock once more?
She was so lost in her own thoughts that she was surprised when he spoke up. "You know, this was pretty enjoyable, old lady," he said, obviously referencing her joke, "wanna do this again tomorrow?"
"Oh, I don't wish to take time from your duty," she fretted.
"Ah, don't worry about it. This bucket of bolts doesn't really need my help to keep going, me being here is mostly paranoia. So, tomorrow?"
Toriel couldn't refuse that logic, not with being so desperate for company. "Tomorrow, then."