I like to ask people what they've tried so far so I can understand their thought process - but also to give them a hint that I expect them to use brain a little bit.
With every client I've ever worked with I always have a wiki page with common Q&A, some "required reading" and links to other wikis / docs.
If people do the incredibly annoying thing of starting conversations with "Hi" or "Hey Sam, how's it going?" Or even worse "Hey, can I ask a quick question?" I politely share this site https://nohello.net if I feel it likely won't be taken with (much) offence.
If they always send you a DM/PM rather than asking in a shared room I ask them to please start a thread in the room so that others can learn and the help can be load balanced, I often link people to this article: http://blog.flowdock.com/2014/04/30/beware-of-private-conver...
If none of this helps and they really are just being lazy - I all have a direct conversation with them and be pretty frank that the value people add to a team / company is the effort and how they go about problem solving - if they're just acting as a middle-person passing questions and answers around it becomes and highly inefficient system.
Not thinking before asking someone else for the answer is a learned behaviour. It can be learned from being out of your depth, low confidence often combined with a lack of context, laziness or general incompetence. Most people aren't generally incompetent but have become comfortable with their learned behaviour.