Loaf, wander idly, as in After graduating he decided to bum around Europe for a year. [Mid-1800s]
Frequent bars or nightclubs, as in Her father accused her of bumming around half the night and threatened to cut off her allowance. In the mid-1800s to bum was slang for going on a drinking spree. A century later, with the addition of around, it simply meant going to saloons or clubs.