I suppose solo (F) and solo (M) really.
My son is growing up and getting to 'that age' now. I always buy him a calender every Christmas, but this year instead of Doctor Who or the usual things I decided to get him one of those bikini babes calendars.
I just bought it as a bit of fun and thought he'd appreciate it. His face went as red as a beetroot when he opened it on Christmas day, but I could tell he liked it and he even put it up in his room before January came round.
I didn't really overthink it before I bought it, but now I keep thinking about what must go through his head when he looks at it. It's pretty tame really, but I know he gets a kick out of having it by his bed. I've never caught him or anything like that, but I'm pretty sure he masturbates over it. I'm sure most boys that age would, and as the house cleaner I do find 'evidence' that points towards it.
I know it's all about the girls in the calendar, but the more I think about it the more naughty it feels that I bought it for him. That I played a part in getting my son turned on and giving him something to get hard and masturbate over. I've daydreamed about him playing over my gift and getting himself off and I've been surprised how much the thought has turned me on. I've even orgasmed myself thinking about it.
So yes, it's a little tame by the standards of some of the stories on here, and I'm sure it will never go any further than this, but it's something I like thinking about from time to time and I feel really happy that I played just a small part in my young man growing up and exploring himself.