Masturbation sleeves won't make any noise. Neither will regular dildos. If it's a vibrator, internal is better - like a love egg (which is inside you) because it will muffle a lot of the noise. The vibrators are good because they're nestled in there as well. Bonus points if it comes with a remote or is app controlled. This means there's less movement on your part - if you are someone who wants to be really discreet.