Depends, I love a women who has either painted or french tips, or black nail polish... What a turn on! if my Girlfriend has this I am turned on all the time, am a hands and foot person... Depends all guys are different..
ahaha. guys are all different and have different places that will turn them on quicker. BUT, if you are just laying down with your boyfriend and you are both fully clothed, if you just give him a kiss on his private part, through his jeans..I'm sure that will turn him on. Like, go down there and kiss that spot and then just look up at him, or go back and lay with him and be a tease.