What Was My Older Sister Doing

So bit of context my older sister is 28 and is a teacher in making but she's always been the hot lady my friends at school loved. Shoulder length brown hair and a pretty face with large boobs and a pawg ass but she's always been the mature one. Anyway she always was the one to pick me up from school since her job finished soon before I did but while waiting for longer than I thought I got a call from her saying her car had broken down, so I asked If I should walk home despite the distance and she said no she'd be there, then she said your friend Tom is looking at it for me.
I said OK then hung up to wait but felt uneasy because Tom was infamous, he was a chubby not bad looking guy but a huge sex creep and overly horny. But he was known to be charming according to other girls.
Anyway It was 35 minutes until my sister turned up and when I got in the car her usually neat hair was a bit dishevelled and she was red in her face and struggled to talk at times. When I asked her what took him so long she just said "nothing, we just took longer than expected." when we got home she was walking strange as well.
What do you think happened? I wouldn't have thought waiting for a car to be repaired would be that stressful.
For anyone wondering Tom took work experience in a garage