If you want a truly genuine experience, insert an grapefruit in his rectum for a few days, and give him drugs so that he'll retain water. When his ankles are swollen to three or four times their normal size, feed him some castor oil, which will cause violent spasms in his intestinal tract. After he's moaning and rolling around gripping his belly for three or four hours, stick a gloved hand in his ass to see if he's dilating properly. You may then take him in a taxi ride and let him moan and groan in the car until you reach the hospital, where you will strip him naked and put him in a hospital gown, hook him up to an IV, and bring various hospital staff in the room to check on his progress.
The pain will be so intense that he will not know whether he wants to sit up, lie down, or cycle through both positions periodically. Let him know that it's a little too late for a spinal block, and that he'll have to pass the grapefruit naturally, but that you'll bring in a doula to massage his sensitive nether tissues so that they don't tear. Tell him not to worry; the human body was designed by evolution to stretch and to handle stresses like this. Bring his mom and dad in with the video camera so that they can commemorate the moment for posterity. After he's blue and pink in the face, his eyes are bloodshot from pushing, and he's pooped on the table a few times in front of the hospital staff, a few hours later, he will have passed the grapefruit, and everyone will oooh and ahh over the poop stained grapefruit while it is being cleaned up, and take photos. Put him in a wheelchair and send him up to the hospital bed, where a specialist will probe and squeeze his pectorals to see if he is producing collostrum, while you text all your friends about the arrival of your amazing new grapefruit.
This experience would only mildly approximate the experience of both pregnancy and birth, a situation that modern women experience voluntarily, and which they sometimes submit themselves to multiple times. This is why it is highly disrespectful for a man to say "we" are pregnant. A man can only just begin to understand the predicament of pregnancy and birth.