The aim of the boredom tesuji is to win a game by reducing the strength of the opponent through boredom. The main resource is generally playing on and on, even if the game is already clearly lost. Supportive means are the destruction of the game by chance tesuji, trick play, unsound strategies, unsound tactics and other offensive bad habits.
Boredom tesuji and stubborn play are closely related, but not identical: Stubborn play is one way to induce boredom, but not the only one. Stubborn play does not necessarily have a malice aim, it may just result from the psychological inability to give in to a loss.
The boredom tesuji is one of the unrespectful bad habits used by people too much fixed on winning instead of playing Go. It sometimes is rated as appropriate for a tournament, but the distinction between tournament Go and true Go should then be clear.
togo: I invented this term after being deeply annoyed by way to much of chance tesuji, boredom tesuji and trick play happening to me online. The problem there is, that stopping playing or giving up disturbs the rating system. And "way to much" means that substantially more than half of my time was wasted. I tried to get something from these games, too, but they just stayed annoying and boring.