Oh, Those Darned Irregularities!
Yes, German has irregular past participles just like English. But you'll find that the German irregular past participles tend to be the same ones that we have in English. They are not all the same, but many are.
The formation of the past participle requires knowing the stem changes of irregular verbs. To the irregular stem you add the prefix ge– and the suffix –en. Look at the steps in forming these past participles.
sprechen/sproch/gesprochen (spoken)lesen/les/gelesen (read)singen/sung/gesungen (sung)helfen/holf/geholfen (helped)brechen/broch/gebrochen (broken)
Once you have the irregular past participle, you use it the same way you did with the regular past participles: conjugate haben and place the past participle at the end of the sentence.
Table 15-3. Formation of Irregular German Past Participles
Did you notice that the last four verbs in Table 15-3 couldn't make up their minds if they're regular or irregular? They make a stem change but add a –t suffix instead of an –en suffix. And, yes, the participle for essen is gegessen with an extra g placed before the stem—one more German peculiarity!