Okay, so Santa Claus is a trucker, and he asked Spidey for help. This is because Trucker Santa wants to make sure that kids everywhere get the chance to buy a fishing rod (and it has to be the right fishing rod, so the kids need their dad’s help, because no way would Mom know anything about fishing because she’s a girl) so they can have a chance at winning a million dollars. And the reason Trucker Santa needs Spidey’s help is because… maybe robbers will try to steal the million dollars! And nobody’s better at stopping robbers than your friendy neighborhood Spider-Man! Because the last time he didn’t stop a robber, his Uncle Ben got shot. God only knows whose uncle would get shot if Spidey didn’t stop the robbers this time!
That’s my best shot at explaining this, unless there’s some early Lee/Ditko issue of Amazing Spider-Man I’m not aware of where Spidey goes into extended detail about how much he loves fishing.