So the simple truth is that back in 1988 the unusual combination of Arnold Schwarzenegger and Danny DeVito worked in the comedy "Twins" and as with most things which work in Hollywood they tried to capitalize on it. As such 6 years later we didn't get a sequel but had DeVito and Schwarzenegger teaming up for "Junior" another comedy. Unfortunately lightning doesn't strike twice and whilst writers Kevin Wade and Chris Conrad came up with an amusing idea of having Schwarzenegger becoming a pregnant man beyond that the movie struggles especially as it runs to 109 minutes.
After investing time and money into researching a drug to prevent miscarriages scientists Alex (Arnold Schwarzenegger - True Lies) and fertility expert Larry (Danny DeVito - Batman Returns) are disappointed when the FDA and their university terminate their research and place Dr. Diana Reddin (Emma Thompson - Peter's Friends) in their lab. Determined to carry on Larry persuades Alex to do the unthinkable and try the drug secretly on himself after impregnating himself with a stolen egg from Dr. Diana's research. But within 4 weeks Alex finds himself feeling all the things a woman would feel whilst going through pregnancy, the sore nipples, the morning sickness and it doesn't go unnoticed as Diana becomes suspicious of them.
So the trouble with "Junior" is that the joke is pretty much watching Arnie experiencing pregnancy as a man. Now initially that is amusing enough as he suffers from heightened emotions and various other things but the joke soon wears thin. And unfortunately when the main joke grows tired there is nothing substantial to divert your attention although there is a daft romantic subplot between Alexis and Diana.
The thing is that there are other jokes going on in "Junior" there is the joke of Emma Thompson as Diana being a bit of a accident prone scientist but is not very funny. It is the same when it comes to Larry's problems with his ex wife who is pregnant. And so not long after it starts "Junior" begins to struggle to really keep you entertained.
The one good thing about "Junior" is Arnold Schwarzenegger who is genuinely amusing as he plays it hormonal and in touch with his feminine side. It's not that the rest of the cast which alongside Danny DeVito and Emma Thompson also includes Frank Langella and Pamela Reed put in bad performances it's just the jokes they get to work with end up quite lame.
What this all boils down to is that "Junior" has an amusing idea and an amusing performance from Arnold Schwarzenegger but it struggles because the jokes are too slim.