Fellow pot smokers, I need your help!

Ladies and gentleman, I come to you with a problem. It's not a serious problem, but something that has always bothered me a little bit about smoking weed, and I'm fairly certain it has bothered others as well. So I'd like to see if any of you out there have a solution to share with me (and by extension, the rest of the world). My problem is that sometimes I get high, and I really enjoy it, but then I don't want to be high anymore. Sometimes I want to come back down to earth. For instance, say I'm at a friend's place in the middle of the day and we smoke a joint. Eventually I'll have to go home, and if I'm going by public transit, I don't want to be high along the way. It's uncomfortable and unpleasant. So, as stupid as this may sound, I need to know if there's anything I can do to get rid of my high and the unpleasant side- and after-effects. Any suggestions at all would be helpful. Now, since I'm not just asking for me, but for the benefit of everyone, please pass on to all of your pothead friends and get them to come and contribute their input. Also, just tell me anything else that's helpful or interesting about smoking weed that perhaps the rest of us don't know. If we're lucky, we'll get a whole weed encyclopedia off the ground.