Shinryaku! Ika Musume, Ansatsu Kyoushitsu Recommendations
Both series prominently feature a strange tentacled invader as a main character among an ensemble cast of "normal" humans, for lack of a better term, and are ripe with ridiculous comedic antics.
First in the endless summer gag category we have Shinryaku! Ika Musume, featuring the title character Squid Girl. She claims to be a messenger of the sea and has come to invade the surface so as to punish humans for polluting the ocean. Unfortunately she is incredibly naive and lacking in knowledge of the surface, as well as easily influenced and pushed around by other humans, such that she got dragged into working