Smurf: a person who goes around from pharmacy to pharmacy buying sudafed (or other controlled drugs containing pseudoephedrine) to use in meth labs.
Two personal notes about Smurfs:
1. In high school, I collected Smurfs. It started with a soccer-playing one.
2. I had a friend in college who was from Cuba, and he pronounced the name of these blue creatures smuf. No matter how many times I tried to get him to pronounce it correctly, he just couldn’t. That started freshman year. Late in our senior year, he told me that he could say it right, but he once heard a Japanese kid say it this way and he thought it was funny. He had me going for 4 years.