difficult
hard
provocative
stimulating
alluring
ambitious
arrogant
audacious
bold
brash
brassy
brazen
bumptious
cheeky
cocky
contemptuous
daring
defiance
defiant
defying
demanding
derisive
disdainful
disregardful
encouraging
energizing
exciting
galvanic
galvanizing
greatly daring
impertinent
impudent
insolent
insubordinate
inviting
pert
piquant
prompting
provoking
regardless of consequences
resistant
resistive
rousing
saucy
stimulant
stimulative
stirring
unchallenging