Would You Breastfeed Someone Else's Baby

I recently babysat for a friend. It is not the first time this precious boy has stayed with me. He is just older now and more talkative. He was so funny. It was time to take a nap and I knew his mom rocked him to sleep. I was looking forward to rocking him to sleep. So I sat down and he started talking about mommy. I reminded him mommy would be back and kept talking. My cat even joined in on the rocking. We must have sat there for 10 minutes talking about mommy with him pulling on my shirt. At first I did not think much about it. That was until my husband came in and pointed at my shirt and I noticed he had not completly pulled my shirt down. I forgot that he calls his moms breast "mommy". I felt so bad that I could not nurse this little blessing to sleep. Poor baby, luckily his mom came back quickly and gave him what he needed. He did fall asleep next to Hope. So my question is would you nurse someone else's baby? I have only been asked once and I said no. I would not just pick up someone else's baby and nurse them. Now if there was a emergancy and I needed to I would without a second thought. I would also donate milk to anyone else who needed it. Pamela