The full caption to this cartoon is "Come on, come on! Stop playing detective and sniff like the rest."
I love this introduction to a common phrasal verb "come on," which in this case is being used to express impatience.
The preposition "on," when combined with a verb, can indicate continuation, as in "go on" (please continue) or "get on with it/ get a move on" (you need to stop idling and start working). Other synonyms for this meaning of "come on" are "let's go" and "come with me."
But don't forget - phrasal verbs are highly polysemous - they have lots and lots of meanings because they are so semantically flexible. It's easy to create new symbolic analogies to the simple "verb / space" combination
Impatience to the point of anger, as in "I can't believe it! Really???!!!!"
Attempting to persuade or change someone's mind, as in "c'mon, can't we make a deal?