Rationality Jokes Thread

This is an ex­per­i­men­tal thread. It is some­what in the spirit of the Ra­tion­al­ity Quotes Thread but with­out the re­quire­ments and with a fo­cus on hu­morous value. You may post in­sight­ful jokes, nerd or math jokes or try out ra­tio­nal­ity jokes of your own in­ven­tion.

ADDED: Ap­par­ently there has been an ear­lier Jokes Thread which was failry suc­cess­ful. Con­sider this an­other in­stance.