Dirty Portmanteau

When I was a student, I used to work as a cashier in a campus grocery store during the summer breaks. We had a campaign offering a free soft ice-cream for every customer with a student card. The day was hot and busy, and while registering the customer payments I had to remember to ask all the students if they wanted the free ice-cream. After a busy customer flow I asked from a young attractive student girl: “Would you like to have a soft sex?” In Finnish, soft ice-cream is pehmis, and for free is ilmaiseksi. I accidentally made a bit embarrassing portmanteau word. The student girl quickly said “No!” to my offer and hurried away.