I didn't know either, so I looked it up. Pomegranite syrup, cranberry juice, strawberries and raspberries were all mentioned.
I would imagine the pomegranite syrup was the first thing used. I'll bet strawberreies or raspberries would be downright heavenly!
Don't care for cranberry juice, sorry.
__________________ We get by with a little help from our friends
Are you sure it was pink lemonade. Lemonade is never frothy or thick and syrupy. Someone must have tinkered with the recipe if you had it at someones house. Lemonade is light and refreshing and pink if you want it pink and that's how I have had it for as long as I can remember.
I would suggest that you ask your friends to buy you an instant lemonade powder (sold again in grocery stores). If you like it pink they can buy the pink one. I believe it's much simpler that way. If they don't you can still make it by using fresh lemons and pomogrenate juice as others recommended.
I normally make mine by mixing the powder with water and also some single string sugar syrup. I dont care for the super tart lemonade so I like to sweeten mine up. Always remember to add a pinch of salt to it as well because it just heightens the flavor of the lemons and the sugar.