It was probably about Dennis's girlfriend Penelope.
Apparently Jenny, Kenny, Gwenny, Benny, Denny and Penny went to one of Lenny's poetry nights at the Dog and Partridge.
Penny - as you would know - is the most emo person on the face of the earth, but this night she actually cracked a smile for some reason.
None of them have ever seen her do that before, and now they're wondering if they ever really knew her at all. Denny is gutted, he's not sure if he wants a girlfriend who is going to go around smiling. She's only done it once but who knows when it might happen again.