I was recently drilling down into a wall at an angle to install a wire. I was going at a fairly steep angle to avoid coming out the wall on the other side, however I was trying to come out the side of the joist. Anyway my bit ended up coming out of the bottom of the joist. The joist was already doubled up and it was a 3/8" bit, do I need to worry about this?

Plugging up would be best to avoid bugs, and the leak can have slight effect on allowing heat, cold, moisture, vapors to pass.

Not sure I understand but it sounds like you were trying to drill through sole plate for wire and had the misfortune to hit a floor joist. You also had the good fortune to come out the side. Should you worry? No, not about that, worry about the price of eggs in China, maybe, but not about that. Run your wire.

I was recently drilling down into a wall at an angle to install a wire. I was going at a fairly steep angle to avoid coming out the wall on the other side, however I was trying to come out the side of the joist. Anyways my bit ended up coming out of the bottom of the joist. The joist was already doubled up and it was a 3/8" bit, do I need to worry about this?
No I did not come out the side, I came out the bottom. It is only a 3/8" bit, the joist is a sistered joist.

Answer is still no, no worry. But you will probably drill another hole so that your wire doesn't have to bend so sharply. Drill an intersecting hole at a 45 angle upper half of joist . Means you will have to feed wire through intersecting hole from bottom up.

I was recently drilling down into a wall at an angle to install a wire. I was going at a fairly steep angle to avoid coming out the wall on the other side, however I was trying to come out the side of the joist. Anyways my bit ended up coming out of the bottom of the joist. The joist was already doubled up and it was a 3/8" bit, do I need to worry about this?
Actually it doesn't bend sharply at all, the angle of the hole is fairly steep and since in my stupidity I came out the bottom the wire pretty much just goes straight up, no real bends at all.

So I do not need to worry about structural integrity? That is my main concern.

Not at all.

I was recently drilling down into a wall at an angle to install a wire. I was going at a fairly steep angle to avoid coming out the wall on the other side, however I was trying to come out the side of the joist. Anyways my bit ended up coming out of the bottom of the joist. The joist was already doubled up and it was a 3/8" bit, do I need to worry about this?
That's a relief, thanks for your help.

I don't suppose you can offer any explanation as to why coming through a floor joist from top to bottom in that manner is going to be OK? Not that I doubt you, I am fairly ignorant to this sort of thing (obviously) and would love to be better informed (for future situations).

Well assuming that there are 2 floor joist because there is a wall above. The doubled joist both give support and give you something to nail the sole plate too. Now given that the joist are nailed together there is still probably a little space between them, lets say 1/16". A 3/8 hole is pretty small. If you drill down the center between the two joist you would be removing less than 3/16 from each joist, lets say 5/32". True the joist have been weakened slightly but not enough to be concerned about. We just don't build to those kind of tolerances. If you look at the joist you will probably see many places where they are drilled and notched. There are rules about where and how large these can be but a 3/8 hole will be insugnificient. If you look hard enough you can probably find a knot parallel to the face of a joist that weakens the joist more than a 3/8' hole.

Ok thanks for the help. I don't know much but try to keep myself somewhat educated, and when I saw I came out of the bottom of one of the joists I was worried that I made that joist worthless.

The only person that does not error is the person that does nothing and that's the biggest error of all.