Theres a trend that existed on the internet awhile ago (probably at least 10 years at this point) where people would share intimate emotional feelings via the method of signs and sad music. They would write out the thoughts on pieces of paper and cry as they went through each one.

Generally with a theme of countering stereotypes or racism or bullying or whatever.

The reason this joke works is that the person themselves thinks they are following the trend while we as the audience can't see the change in paper since they are lowering the one closer to THEM and not the one close to US. Which is an inherently dumb thing to do and so its counter to the "countering stereotypes" aspect of the original trend.

Think of it like "they say all strong men are dumb but im smart enough to know that 1 + 2 = 8