<human>: Give me the gist of the text in a nutshell

This actually happened a couple of weeks ago if it matters. I was bored on Facebook one night so I decided to post an emoji-fied version of [some artwork from an album I liked.] (Make sure you see the artwork first, it's vital to the FU.) Anyways, the closest I could get to the gesture seen on the artwork using emojis [was this.] If you don't yet see why that's obscene then maybe you need to have "The Talk". (Get it now? If you STILL don't, 2 words. FINGER SEX!) At the time I was posting this, my stupid brain didn't think AT ALL about how this gesture might look to someone who knew nothing about the album artwork. The real kicker here is that I posted the emoji gesture accompanied by nothing else and with absolutely NO CONTEXT whatsoever. 

Anyways, I post the gesture and go away for a while. I come back to Facebook and see that my friend's sister commented "???" on my post. At the time, I just thought she wanted to know what the gang sign-esque gesture meant. (I still didn't realize my terrible mistake yet) I showed her the artwork and she seemed pleased with my explanation. No other likes or comments on my post except for the one already mentioned. Fast forward a couple weeks and I am talking to my friend on the phone. (His sister is the one who commented on my post.) He eventually brings up my post and asks what it was supposed to be. I told him it was the aforementioned artwork made in emojis and he starts laughing hysterically. He says something to the effect of, "You DO know what it looks like, right?" At this exact moment my brain put 2 and 2 together and I suddenly realized I had fucked up. At first I rationalized maybe it was just him, but it turns out his OTHER sister saw it and assumed it was a symbol of emoji finger sex. I can only imagine the amount of people who must have seen my post and thought I was being an immature douchebag. Maybe it's why I lost a few friends on Facebook not too long ago.
<bot>: I post an emoji version of some album artwork on Facebook, weeks later my friend helps me realize it obviously looks inappropriate, embarrassment ensues knowing a bunch of people saw it.