Curvy girlfriend surprises with ass play on my birthday

Celebrating my birthday, I invited my girlfriend over to my place. She brought a balloon as a gift, which I found quite lame. But little did I know, she had a surprise in store. As we started getting intimate, she unzipped her dress, revealing her stunning, natural big tits. I was taken aback by her beauty. She then proceeded to tease me with her ass, making me crave for more. Unbeknownst to her, I had a kink for watching my girlfriend get fucked. So, I sat back and let her know about it. She agreed to fulfill my desire and called another girl over. The girl eagerly agreed and began to pleasure my girlfriend's tight ass with her tongue, while I watched in awe. The sight of my girlfriend's moans and the other girl's tongue delving into her ass was a sight to behold. I couldn't help but get turned on by the sight, and the other girl soon took over, giving my girlfriend's ass a thorough fucking.