That's not fun. That's smoking, drinking and having sex - adult activities, not the regressive infantilism one usually associates with "workplace fun."
If you smoke at your desk, someone will complain about catching secondary lung cancer or it might trigger an asthma attack. Also, the workplace will stink of cigarette, cigar or pipe smoke - not a good sign if you're trying to win a contract from a health store.
If you drink, you'll get drunk at work. Fights could break out, and you'll screw up work that you should be concentrating on. And if you have to get into a car and take off for the client at a moment's notice whilst still drunk, that's deadly lethal.
Other kinds of drugs? Not really. Drinking at work is close to lawbreaking especially where you might need to drive to a client, but smoking a joint in the office is right out.
As for sex ... forget it. You're not going to work for that. You go to work to earn money for you and the company. Where does that sort of adult activity end? Do you allow open displays of sexual activity? Does your firm only allow straight affairs, or do you still go all Victorian if two lesbians or two gay guys take off on some torrid affair, all open public displays of affection in the workplace?
Think about all those employees at your workplace. Think of the one or two that always crop up, even in the most enlightened offices, who will sneer and grumble "Disgusting" under their breath at the sight of two guys locking lips in the copy room.
I know that firms need policies of fun at work to prevent them becoming grim, isolated monasteries. But smoking, drinking and sex are not the best choices of "fun" to allow in the workplace, any more than conversations about sex, football, politics or religion at the watercooler.