When a person doesn't understand you, you have two alternatives:
Adapt the vocabulary according to what the person knows or not,
Explain to the person the terms she doesn't understand.
The first case works well when the person knows already the technical vocabulary quite well, but not enough, or not in your domain.
For example, you may use the term method in C# or Java, and the person who mostly works with some other language would not understand this term. You will then explain that in C# or Java, method is referring to what we usually call function (for example in C), and that there is no such a thing as function in C# or Java. In PHP, for example, both methods and functions exist, and have a different meaning. If the difference is too painful for the person, you will talk about functions for the sake of simplicity.
In your precise case, you can hardly choose the first one: "make a call to the function" cannot be reformulated in any simpler way. A call is a call. You can't simplify this more.
This means that you have to choose the second way: explain to the person each technical term.
Either point the person to a dictionary or Wikipedia, which works very well for basic concepts and terminology.
I would choose this for commonly used terms. For example, I would rather invite the person to read Wikipedia to understand what is polymorphism, or what are covariance and contravariance. Those terms are already explained very well, so don't need to reinvent the wheel here.
Or explain in your own words.
I would choose this for terms which are specific to the context and/or accepting wide range of definitions. For example, Wikipedia is not very helpful to understand the Microsoft's vision of cloud computing, and I would rather explain myself what is cloud to somebody who will be working on a Windows Azure application.
In your particular case
The people you are talking to are lacking the most basic concepts and terms used in programming. They can't continue without learning this core vocabulary, because they are unable to communicate at all: they can't read books about programming or blogs, they can't listen to their colleagues, and they even can't really ask questions on Stack Exchange websites, since nobody will understand what they are asking.
In your case, rather than searching for suitable vocabulary, I would spend a few days or weeks teaching them some core programming concepts and the commonly used terms. After a few days, you will be able to talk to them without being required to constantly "draw them pictures and use metaphors involving cats and dogs".