A container for lemons
Despite its slightly psychedelic depiction, this is in fact a very well known groan-inducing pun, a “dad joke” of the highest order.
It stems from a colloquial shortening of the Japanese word for “thing” (mono -> mon). The word for “container” or “holder” therefore becomes “iremon” rather than “iremono”, to combine delightfully with the Katakana reading of the western word for lemon.