Does randomly doing a moderate set of training throughout the day have any benefit as far as a very skinny guy trying to make moderate muscle gains? For example, hitting off 50 situps and pushups or some bicep curls about 3-5 times randomly spaced throughout a day?
thanks

No not to any real extent, Get a structured routine. That will be beneficial.

Technically, it will have an effect, for the first few days. After which the body adapts and no longer benefits from the erratic pattern. Intensity needs to increase, and plus, the body needs to get ready to exert force, and doing so for a few minutes a couple of times a day can make it go whack. Try to organize yourself as much as possible.

-Roek

sure, some sit ups and push ups everyday will do you good. Though I would suggest a balanced training for overall body, not just biceps curls. I know a flexed biceps is the first thing you would notice, like Roek's avatar, if someone is well muscled or not, but for instance, you can't have a truly strong, well conditioned arm if you don't work your shoulder(deltoids), triceps, and forearms at the same time. Then well conditioned arm won't look as good if your pecs and lats are in a poor state. Try to pay attention to the overall effect, and put some variety in your routine everyday, and do not work the same muscle groups every day, which will just exhaust the muscles and prevent from an effective gain.

another important thing to take into acount is that when you do an exercise - be it sit ups or pull ups or whatever- you do them to failure; this means that you do them till you can't do another one correctly. it's when you've taken your body to it's limits that it'll rebuild it'self stronger. Try to make the exercise difficult enough so you can only manage to do between 8 and 12 repetitions to every set (this will give you increase your strength and endurance)
if you don't have much time or enthusiasm to start with, you can work a lot of muscle groups with a few exercises; wide pressups, pull ups, wide squats or lunges, sit ups, shoulder press (with dumbbells or something like that).
if you start off with something simple then you can improve it as you go along and you wont get bogged down at the beginning with all the stuff you need to know.
alternatively, you could join a gym and get them to write you a routine to start off with.

Put it this way, doing 50 reps of bicep curls at 9 ,12 ,3 ,6, & 9 o'clock [ 5 times ] each day simply makes no sense from a number of perspectives.

To add muscle, train a bodypart once a day on non-consecutive days. And if your goal is optimize muscle growth, the rep range for hypertrophy is around 6-12. Sets can be from 3-5.

I dont really think the "random" pushups or situps will help that much but if it makes you feel good than you can.

I wouldnt do the bicep curls tho I would save that on my workout days

pretty much would be doing nothing for u, i think thats a waste of time
id try to settle into a nice routine, and a good diet