Dadaism is an art movement... it's hard to describe Dadaism as anything but random. Here's a recipe for a Dadaist poem:
1) Cut out words from a newspaper until you feel you have enough
2) Put all the words into a hat
3) Roll several dice to determine how many words the poem should have (2d20 should be enough
)
4) Shake the hat until you feel the time is right
5) Now pick the appropriate number of words out of the hat, writing down each one. If you feel you do not have enough when you are finished, or if you feel you have enough when you aren't finished yet, you may ignore the number you rolled previously. This is your poem.
Alternatively, you can take a big book (a dictionary, preferably) and randomly open the book and point to a random place, and use the word you are pointing to.