More than a quarter of the 600 people questioned said that using too many expletives was their biggest vice, the survey by ECigaretteDirect.co.uk found.# Drinking too much caffeine came second in the poll, with 18 per cent saying their tea and coffee were the hardest thing to quit. Chewing fingernails was third, with 15 per cent, while 13 per cent said they could not give up watching television and 10 per cent said smoking was the habit they wished they could kick.