When a subject and/or class, usually in higher education scientific fields, is so convoluted and hard to follow, that it is impossible for one to succeed in it. This might be due to the professor, or the subject itself. In this case, the subject acts as a filter, preventing you from moving on to more advanced subjects that built upon it.
This can often extend or apply to specific concepts included or related to a subject or class.
In any of the above cases, it is fair to say that one has been filtered.
-Did you understand anything from the previous lecture?
-No, I'm not even sure the professor understands what he's teaching.
-Huh. I guess we've both been filtered.
Nickname given to bales of marijuana thrown overboard or out of airplanes. Origin is reportedly from members of the US Coast Guard in the area of Southern Florida.
A sunburn or suntan focused on the left arm. It is caused by the left side of the body being the only half that gets exposed to sunlight while driving. Presumably, it would be located on the right side of the body in countries where they drive on the left side of the road.
I had a trucker's tan after driving for 10 straight hours on a sunny day.