I think it would be a good idea for me to put dog poo into an old lady's bin.
What would make you want to do something like that?
I saw her doing it and think I should do it as well.
It's not okay to use someone else's bin for dog poop. It's a service people pay for so they feel a bit exploited when others have left their dog's poop literally at their expense.
Eh. Can I be honest?
Yes you can be honest and say what is on your mind. Just realize that poop is very nasty, and putting something like that into someone elses property is pretty terrible. This could completely ruin the product itself.