Ouch...I fucked my best girlfriend's boyfriend

My best girlfriend was travelling and she asked me to look after her apartment in the meantime. As I walked through the apartment, I found her toy box. I didn't know anything about it, but I liked one toy and I made myself comfortable on the couch and got horny with a big black dildo. Suddenly her boyfriend was standing in front of me, dressed only in a towel. Oops, I didn't know he was in the apartment. It was an awkward situation but it somehow excited me and apparently him too because he was building up quite a hard-on ...... so I got up close and personal.