On Thursday, President Donald Trump stressed the importance of a particular feature of his proposed border wall: transparency. His reason? Without it, a 60-pound bag of heroin might fly over, and hit an unassuming passerby on the head, striking them dead. The vivid image invites flashbacks to Chuck Jones cartoons, and more than a few questions. But to take it on its merits: Yes, drugs do fly over the wall. But … not like that.