I can't find this manga. It's a part of a non-compiled series.
A boy visits his girlfriend's house for dinner. The girdlfroend's mom opens the door in a sexy split-front dress. The giflfirend's mom starts hitting on him. Girlfriend leaves and the mom starts giving him a wild BJ under the dinner table. Girlfriend comes back and says how jealous she felt and starts making out with him without knowing the mom is under the table.
Black and white. Read it a few years ago. Anyone know it?