It’s a sex joke. Two sponges, a rubber glove, and some lube can aparently make a reasonable at home fleshlight. You take the sponges and place them at each side of the glove wrapping the hole around them to keep it firm before placing it in some tube, say the provided image of a man portable recoilless anti tank missile launcher, and use the lubricant to allow a persons erect member to enter this unholy contraption.
The idea is that you are between each sponge which gives pressure while the glove provides a slick surface. The m1 rocket launcher provides a sturdy structure to contain it all.