a. lose their friends
b. get on the wrong train.
c. get on the wrong train, with their friends ticket, leaving said friend at the station.
d. take their mobile with them so they can deal with it themselves.
e. book into a b&b and not come home and irritate me.
f. not come home and get all uppity and arsy about nothing and irritate me even more (which hasn't yet happened but if it does I swear this may end in divorce).