Learn English – thrive in vs thrive on

To use X - X here has to be a tool, and to use X will mean do an activity where X will help or is needed to accomplish that activity. E.g.: Use the pen to write down what I say. A pen is a tool that is needed to accomplish writing.

To make use of X - This is like to use X except that X is not necessarily needed to complete the activity in question, but it will help. E.g.: Feel free to make use of anything in my spice rack when you start cooking. The spices might help, but aren't strictly required.

To tap into X - A physical tap is something that allows one to draw out or extract water, liquid, or other similar resource from a stream, network, or container. Following this logic, tapping into something can mean attempting to draw out or extract something needed (from someone) that can help you complete an activity, and this something will not be a physical object but a mental resource such as knowledge, skill, social connections, etc. Tap into your customer service skills when dealing with difficult requests.

So ...

A market in my opinion at least, that can be tapped into. Graduates would more likely be something made use of unless your location is starved for the skills of this specific group of graduates. Tap into X somewhat carries the subtext of X is needed by us but not vice versa.

And,

Can you make use of these papers?

Can you use these papers?

The difference in meaning depends on what the papers contain and how useful they are to the person you are offering to them. If you think they will help, but aren't required, make use of is appropriate. If you think they are needed by him to accomplish his task, use is appropriate.

To blow a man is to perform fellatio on him. To "blow on" someone is simply to release a puff or stream of air between your lips in that person's direction from a point of close proximity. There are three jokes here:

1. The mother probably said "you don't know whom I had to blow to get the reservation," humorously implying that the only way she could get the reservation is by exchanging a sexual favor. (Well, it's more likely that she said "who I had to blow", but hey, I'm pedantic.) It's not uncommon to make that sort of jokey comment. For example, if I obtain a rare, out of print book for a friend who very much wanted but couldn't find it, I might say "I had to blow the previous owner to get it."

2. It's possible that the mother deliberately says "blow on" instead of "blow" to avoid the sexual meaning in conversation with the nine year old. Or she did say "blow" but he does not get the sexual reference, and assumes she said "blow on". Either way, the idea of blowing on somebody is silly, of course, particularly in the context of using that action to get a favor. Part of the humor lies in this fact.

3. Finally, the incongruity between the sexual nature of the actual statement and the innocent, silly understanding of the child provides another level of ironic humor.

Two notes in closing:

• Do nine year olds really not know what blowing someone means? The author has a less cynical view of kids that age than I do, I suppose.

• The term "blow" for fellatio is quite weird. An old joke involves one guy telling another: "Suck, you moron, suck; it's only called a blow job." An answer to this Quora question suggests that the name "blow job" itself started out as humorous, since it deliberately uses the opposite of suck to refer to an act that involves sucking.