If you're like me and missed the chance to get this achievement from the "Night Market" and "Club Bam Bam" missions. Well, I have included a photo of the in-game world map, highlighting a location you can visit anytime during your gameplay, that contains two fish tanks for you to break and then smack someone to death with a fish thereafter to get the "A Slap in the Face" achievement.
You might have to zoom in on the map I've provided, but I tried really hard to clearly point out the fish tank's building location and an easy point of access to get into this building. Please disregard the blue direction line on the map. If you try to set a waypoint marker to this building you end up with those directions because it won't take you directly by car to the building because it's inaccessible by car mostly. So, I would just try to set a marker close to where I put the second yellow arrow in the photo that says "Easy Access From Here", or something akin to that.
I couldn't figure out a way to post the map photo directly in this post, so I've linked the photo from my Public Dropbox folder. I hope this map I created helps out people who missed this achievement during the missions and I can absolutely verify that you can get the achievement this way because I just did. Again, I hope you find this info. helpful, thanks.
Link To Fish Tanks Building Map:https://www.dropbox.com/s/v1a353u0qnj2rlm/aslapintheface_fis...
If the link doesn't work for you for some reason (I just pasted it into my browser and it worked okay for me), please let me know and I'll try to figure out another way to share the map photo for getting this achievement. This is the first time that I've ever posted anything to this website so I hope this works okay.