After spoonerisms, portmanteaux are my favorite form of word play. They are a combining of multiple words into one. For example, a weirdalfternoon is an afternoon spent listening to Weird Al. Unfortunately, linguists no longer use the word "portmanteau" but call them "blends". That's dumb, because its a terribly boring name for such a fun thing.
Spoonerisms, my favorite, are simply an interchange of letters/sounds among words in a phrase. For example, "wild turkey" is said as "tiled wurkey" (written as you pronounce it). You can get more tricky (and fun!) by exchanging vowels or consonants in the middle of words, or exchange more than two sounds: "Chinese Gourmet Buffet" becomes "binese chormet guffet" (say that three times fast!) and "drugs & alcohol" becomes "hugs & dracula"