I work in an office, and after meetings, there are often spare sandwiches that are offered around.
I work in one group. A group of people of a similar level, all friends, were talking today and someone mentioned these sandwiches were brought to their group by a female member of staff, and also friend. A friend in another group mentioned sandwiches also came around to their group by a female member of staff.
A male friend in my group quipped about the member of staff who brings them around "what a slag!". A few of us laughed, one friend found it really offensive.
I think among friends, it was obviously a joke on the "promiscuity" of sandwiches, but I'm prepared to admit I was wrong to think it wasn't offensive. It wasn't very professional, but among friends?