I once walked in on a raid at a friends house, over 15 years ago now. I knocked on the door and my friend answered and said (in a loud, very clear voice) "FUCK. OFF." They this other guy (plain clothes) walks up behind her and says "naah, guys, come on in". I knew something was up when I saw his .38 on his hip...
We just had to sit in the lounge room for a few hours while they searched the place. Then when they left, my friends busted out the drugs and went to town. It would have been the safest place to smoke drugs that day since they aren't gonna be able to get 2 search warrants in one day...