A person who can't or won't pay for their own drinks, who hangs around outside cafes or in pubs in the hope that the paying customers will leave a glass or cup with some contents they can consume before the staff remove it.
A person who is constantly fishing for answers from others and never actually contributes to solving problems. A driggler will often accost you just as you're in the middle of working and ask you to answer questions that you've answered many times before.
"Oh man... I was driggled so hard by this guy last night, that I couldn't get any studying done for my exam."
"Yeah.. that driggler just doesn't know when to stop!"