Reading a poem is a real thing, a worthy thing. So to be there right with the reader at that moment is part of the effect of a title like "Poem for" something or other. Matt Rohrer does this a lot in his titles, and I think I might have gotten some of the idea to do this, or at least been reminded of how it can work, from his recent amazing books.
I am intrigued and even moved by the idea of being right with the reader in the actuality that she or he is reading a poem. So the titles are an acknowledgment of the reality and value of that act in the world.
I just know from experience that reading a funny poem aloud, especially at the beginning of a public reading, can have a certain effect. Somehow narrowing the spectrum of possible emotional reactions. So while I like it when people laugh at my poems, and I definitely enjoy being funny in them, I don't really think that's the most important thing that's going on, at least not to me.