I saw a homeless man asking for change and put a dirty tissue in his cup instead.
Gross. Why would you put a nasty tissue in there?
I took the tissue back, so no one will really know what I left in there
Even if you took the tissue back, it is still wrong! It is not okay to put tissues in the cup!
Whatever, and I don't care if homeless people get sick.
I don't care who the person is or how you feel about them, as despicable as that is, you shouldn't try to spread disease. Especially in today's world where Covid is spreading, you could cause very unintended consequences just thinking you're being funny.