This "quick tutorial" introduces the general idea of a call and explains the most common cases. It does not explain or illustrate all cases. For additional details and/or examples, refer to the links in the "MORE INFO" box.
They then do the other call from that position. Note that the action of the two calls is typically blended together -- the dancers don't actually line up neatly holding hands as a couple before starting the second call.
Here are some examples:
Explode and Pass Thru
Explode and Touch 1/4
Explode and Roll
Be careful not to confuse Explode and with Explode the Wave. "Explode and" doesn't include the pull-by action. (Explode the Wave is equivalent to "Explode and Pull By".)