Public Places Ruined by Cheap Love Acts in Karachi

It's sad how public places are being ruined by so called cheap "love birds" in major cities of Pakistan specially in Karachi.. I went to a restaurant the other day with my nephews and a young couple were shamelessly involved with vulgar activities.

If I live in a western country I probably would have tolerated it (disgracefully of course) but not here when I have kids with me.. I wanted to get up and call the manager but my sister asked me to mind my business.. what would you do in this situation, is minding our business is the only way?? What else should i have done so it won't happen again.. at least not infront of kids?