1. "You smell great, like a lumberjack that rolled around in a puddle of Nutella." If there's one thing romantic comedies have drilled into guys' heads, it's that they need to smell like fresh sandalwood and boysenberries so that when they inadvertently leave their shirt at their girlfriends' house, she can spend all day smelling it and staring at the ceiling and pining for them. It makes guys feel really good when you act like they smell like anything other than Irish Springs bar soap.
2. "I feel safe with you." Men want to feel like a giant cuddly teddy bear/murderous black bear hybrid. This one covers all the bases because it's like you're telling them you feel safe in their arms, but you also would feel safe in the event that you were both attacked by a wolf.
3. "Have you been working out?" Just pretend he has muscles, OK?
4. "You're really handy around the house." Blame the far-reaching and deeply ingrained dogma of Home Improvement, but it's manly as hell to be able to fix a sink or refurbish whatever it is you refurbish (chairs?). If you can make a guy feel like he's Ty Pennington just because he wedged a book under that wobbly table, he'll feel great for weeks.
5. "You have a nice butt." Just because, "Hey, nice penis!" sounds creepy. And who doesn't want a nice butt?
6. "You dress so well." Most men don't know how to dress. If he ever tucks his dress shirt into his pants, he probably thinks he pulled off a Justin Timberlake-level move. Congratulate him on having the fashion sense to not look like he just came off a week-long bender.
7. "Your job is so cool." Most people don't really like their jobs, and the fact that they spend a lot of their life there is pretty depressing. Hearing you say you're actually jealous of what they do for a living is a great pick-me-up.
8. "You crack me up." According to Pinterest, Marilyn Monroe once said, "If you can make a girl laugh, you can make her do anything." Like date you.
9. "You're so good at going down on me." Men are still stuck with the antiquated notion of being providers, and that includes providing orgasms to your vagina, dammit. Men need to know that they are the best orgasm-giver you have ever been with and further, that everyone else has a smaller penis.
10. "You have the most kissable lips." We are just programmed to back away slowly when you start giving compliments about physical appearance. This one is OK though because it also means you want to kiss us.
11. "You really turn me on." Telling your boyfriend that you not only find him physically attractive, but that you actually have to physically resist the urge to jump his bones all the time is the second-highest honor you can pay a man. (The highest honor is knighthood, obviously).