How do you spell mistletoe?

There is no such verb as to mistletoe. Mistletoe is a decoration, like holly, so the term decorate, or festoon, might apply. If there were a verb form, it is unclear whether it would apply to the act of decoration or to the social custom (kissing beneath it).

Nonetheless, the term mistletoeing is used as a Christmas rhyming Word in the song "It's the Most Wonderful Time of the Year" popularized by Andy Williams.