i have had this question on my mind for a while. my dad thinks im wrong so I want to make sure. are plastic tupperware-type containers acceptable for housing reptiles

Absolutely! They work well for reptiles, some more than others ofcourse. Plastic keeps humidity in really well, so they are excellent for herps requiring higher humidity levels. They also keep in the warmth quite well, although they wouldn't really be suitable for reptiles requiring very high temps as they are difficult to use bulbs and CHEs with.

We house our 7 corns, 2 king snakes, 3 BPs, 2 BRBs, 2 boas, a blood python, 2 western hognoses, 2 irian jaya carpet pythons and a leo gecko in plastic boxes of various sizes. In fact, the plastic boxes are better for some of our reptiles - the BPs and blood python are shy snakes and the lower height of the enclosures makes them darker and a more enclosured space, meaning the reptiles feel more secure in them. In our blood python enclosure we have a smaller plastic tupperware box with a hole in the lid for her to hide in - most of the time we find her squashed into this small box, it is obviously more secure and comfortable for her.

We have come across people in the past who think the plastic boxes are not as nice as other enclosures, and are even cruel! How can they be cruel when they are the same size as other enclosures, but simply made from a different material?? They simply may not look as aesthetically pleasing as other enclosures, but they are often more practical, for example we have a rack made out of plastic enclosures, which saves a lot of space.

An acquaintance of ours even once had a snake that didn't eat for many months. He put it in a plastic enclosure that was only just big enough for it, and sure enough it ate! He moved it back to a larger more open enclosure and it refused to eat, but once again back in its plastic box it ate every week without fail.

So, once again, in a word, yes, plastic tupperware boxes are fine for housing reptiles.

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"If you know everything you may as well blow your brains out because the reason for existence is to learn more everyday." - Mark O'Shea, 2004

I agree. The plastic tubs are fine. I use them for my colubrids. The rack systems large scale breeders use are based around them. You can find them with clear sides too. They are durable, inexpensive, light weight and easy to clean.
As Rachel pointed out the only drawback is if you are using a high temp heating device like a Ceramic Heat Emitter. They don't take high temps well.

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Merlin,
What's Life Without A Little Magic!

so I just drill some holes on the side and top?

I drill 2 rows of holes 1/8-3/16 in diameter about an inch apart in a zig zag pattern down both the long sides in the upper 1/3 of the box. If you are housing hatchlings you should use smaller holes.
I also use strips of velcro in the center of both long sides to make the junction between the side and top more secure.

__________________
Merlin,
What's Life Without A Little Magic!