If you have a penis and want to use a harness, the Deuce harness is a great choice for you. Designed by the fine people at Spareparts to accommodate folks who want to strap it on and have a place for their natural-born goodies to reside.
An internal pocket holds a vibrator for extra stimulation, and a unique pouch comfortably cradles the testicles. Leg straps lightly cross over the perineum for added pleasure. Comfortable and completely adjustable, it can be worn for extended periods and makes a great option for those with erectile dysfunction or not interested in penetrating with their own bits.
Can also be used for double penetration! Top hole is for dildos, bottom hole is for your cock (or another dildo...).
See below for some suggestions on dildos that fit this harness.