The Meet 'n Fuck games says in order to get to the CUM button, you need the item she is attached to in a sexual way. Then you go for the tighs before the breasts or she will get angry, after that you should find wich of her breasts makes her horny as fuck while you avoid the other one, this is important since it changes depending her mood.
Why bother ever getting turned on by anything when you can spend your time on greater pursuits like creating a robot army? Sex is lame, go for robot attack and human subjugation.