The CDW document entitled Redemptionis Sacramentum has the following serious paragraph (my emphasis):
[92.] Although each of the faithful always has the right to receive Holy Communion on the tongue, at his choice, if any communicant should wish to receive the Sacrament in the hand, in areas where the Bishops’ Conference with the recognitio of the Apostolic See has given permission, the sacred host is to be administered to him or her. However, special care should be taken to ensure that the host is consumed by the communicant in the presence of the minister, so that no one goes away carrying the Eucharistic species in his hand. If there is a risk of profanation, then Holy Communion should not be given in the hand to the faithful.
Over at Da Fidei Quae Fidei Sunt there is an account of what might have been some receiving (in the hand) a Host at Communion and then instead of consuming It, leaving with It, over the protests of concerned Catholics who questioned him about what he was doing.