'Tend
A friend invited me for a meal this Shabbos because it was her daughter's last week before going away to sleep-away camp. Her daughter is very sweet. We have a lot in common - both of us are the oldest children with only younger brothers and no sisters. Her daughter asked me if we could be "pretend sisters." My friend was a little disturbed by the thought of this as she herself is only a year older than me and would have had me kinda young. But it was cute. Her daughter said that she heard a story about someone who used to say pretend "'tend." So we decided we would be "'tend sister." Finally, a sister!