the examples are:
-deciding whether a second burger is worth the extra $2
-deciding whether the overtime pay is worth working on your day off
-deciding whether to pay a fine for polluting the local harbor or installing antipollution machinery
In rational behavior, our decision-making process is always based on which decision give the maximum/optimal benefit for use, after deducting all possibilities with a logical approach.
All the actions above represents this very concept of rational behavior.