The best way to deal with teasers is to play an attacking defence ;-)
When they say ohh why aren't you drinking are you pregnant or something, just seriously reply "yes I am! Thanks for noticing!" They will all be stunned n whatnot... "Reaaaaaally???!" Just be like "haha no of course not". That way you catch them off guard and you make it sound so unrealistic because you ARE agreeing. I know that comes across weird when I write it, but it totally works. I have one specific cousin in law he always says it's ur time, are u utd yet, why aren't u drinking etc. now I just totally mess with him. "Oh yeah I'm 12 weeks tomorrow. I was gonna announce it tomorrow thanks for ruining the surprise. We have decided if it's a boy we are naming him *insert cousins name here*." Etc etc. confuses them enough for u to make your "don't be silly" remark and bail haha.