First of all, sorry for mistakes, English is not my first language.
So, me (M20) and my gf (F19) (lets call her Amy) have really cool relationship. We basically only fuck and drink together. Kind of a dream for any man.
Amy: 5.5′, thick ass, decent tits, slim waist, long light brown hair
Me: 6.1′, a bit overweight , 8” with solid girth
So, one day we were drinking in a pub. Just how we normally spent Friday evening and after that (both slightly horny) we decided to go to her. When we arrived, her mom was at the dining room watching TV with opened glass of wine and wearing just her bathrobe. (She was not that drunk I would say) So, we joined her. Amy took a seat and I sat next to my MIL on the couch.
MIL, lets call her Nancy: 45yo, blonde hair, slim, decent ass and tits (her husband was away on a business trip)