A time (te)suji is a colloquial expression for playing a forcing move, wasting some aji, during overtime in order to avoid losing on time. The opposite action, playing a complex move when your opponent is in time trouble, may be called a time stealing tesuji.
In amateur play, it is not uncommon to play incorrect time-saving moves due to time pressure. In professional play, it is rare. Such an extraordinary occurrence from a professional game between Lee Changho 9p and An Cho-yeong 7p from 2002 is included in the book Weird and Wonderful - Volume 1 - Extraordinary Moves by Professional Go Players.