In all seriousness don't feel guilty.
All of the mainstream charities advise people not to give money to people on the streets. In the vast majority of cases it will just be spent on alcohol-drugs, and it perpetuates the underlying reasons why these poor individuals find themselves where they are.
Best to donate to Shelter, The Salvation Army, and other organisations doing great work out there.
I once bought a homeless person mini beef pasties.. Was probably fuming and wanted money haha