The moped of the second example is a pun, one of whose meanings is the same inflected form of the verb mope ("to sulk") and the other of which is the noun moped ("motorized scooter").
these observations confirm the concerns we raised in §2.2 that pun disambiguators, unlike traditional WSD systems, cannot always rely on the output of a lemmatizer or part-of-speech tagger to narrow down the list of sense candidates.