I think we had this YKTTW a long time ago, but apparently it never got launched?

Anyways, a common Ship Tease device in anime and manga. A character sneezes or dirties himself in some way, and a girl lends him a handkerchief to clean himself up. Cue wacky hijinx as the guy tries to return the handkerchief later, cleaned and dried, to the girl. He will almost invariably be incredibly self-conscious about the act, because the girl who lent the handkerchied is either his crush, or the afflicted character is aware of the trope's romantic connotations.

I don't know how realistic this is. Do girls in Japan tend to carry around fancy decorated cloth handkerchiefs? I'm one for disposable paper ones, myself.

Only two examples that immediately come to mind are the Aneimo hentai anime and the last episode of The Melancholy Of Haruhi Suzumiya, where the trope is...averted?, because neither Tsuruya nor Kyon seems to pay much attention to the handkerchief.