Curiosity the cat (and me)

My sister (who blogs here) has messaged my friend (who blogs here) to ask for her mailing address. My only role in this transaction is to pass the address on (which i have now done!) I feel like a middleman in a drug heist here, and now i am curious- Why??

What is my sister sending my friend??? Now i am living with the curiosity until one of these guys fills me in!!!