Ever since Dan's unfortunate accident at Ile Du Diable, extremely fantastic and improbable events seemed to start following him around. Within the first five issues he had his Metropolis brownstone torn down by the criminal known as Shockwave, saved S.T.A.R. Labs from a megalomaniac bent on world domination named Metallo, arm wrestled with Superman, released a newly powered Nebiros, and joined the Mexican army. On returning from the battle in Mexico, Dan and Norm stopped off for a bite to eat right outside of Las Vegas where Norm proposed his theory of the "weirdness magnet." He blamed it on the "mixture of magic and science." Right after that, aliens popped out of the microwave.
For a long time, the theory remained as something of a joke, though nevertheless, one that seemed to be true. It was only sort of confirmed much later on by Cain. When Dan pulls a muscle in BLUE DEVIL No. 29, he creates a weirdness leak, to which the House of Weirdness has a reaction. The House creates antibodies to fight off the infection. Cain describes these mite-like beings as being opposite in polarity to Dan's weirdness. Consequently, when one of the professors from the Institute of Hypernormal Conflict Studies becomes possessed by this opposite weirdness, Dan is repulsed when he attempts to tackle him. The story is slightly confusing on the nature of the two kinds of weirdness, but the point is made that weird things are very literally drawn to the Blue Devil. It's a cute concept even if it doesn't make a whole lot of sense.
We also know that weirdness has an effect on whatever energy is used to determine the course of the Gorilla City stargate. When Grodd attempts to use said stargate to get to get to Central City, his transporter beam thingy is hijacked somehow by the energy flux created by Dan leaving the door open to the House of Weirdness.