Fragmentation should be outlawed.

Is there a way to disallow fragmenting from ever happening on my computer, my RAM, my thumb drives?

It's simple - Don't delete anything and you won't get fragmentation! Really, there is no way around fragmentation at least in Windows, but as others have stated, periodically run defrag, you should be fine. The only time you will have performance issues is if you have not done any defrag maintenance on it. Also, anytime you copy one file, it is opened and closed once, whereas if you copy multiple files, the system opens/closed each file as it is copied to another location - no way around this either.

Not exactly on topic, but maybe an interesting controversy on (de)fragmentation: Floating around the net in various forms: A reply with alternative views on the issue:

but... i thought defragging SSDs is a good way to ruin them? defragging doesn't achieve anything if your random access time down in the nanosecond range...

defrag and system performance linked, survey says! 

operating systems need to develop a feature that forbids fragmentation, the penalty being reduced disk space. software programming needs to be developed that makes every program and every file a fixed size. software, as well as files, should follow the same rules in terms of size as monetary currency. such as: Bills, quarters, dimes, nickels and pennies. these sizes should be based on media sizes through history such as floppy disk size, cdr size, dvd size, dual layer dvd size... stuff like that. then, hard drives can be classed according to exactly how many mp3s it will hold, or how many divx movies it will hold, etc. instead of a definite size, it will have a relative size. hard drives should have fixed partitions for each media type, whether it be a program, a dll, a pdf, a jpg, an mp3, a video file, a wav, etc. statistical data can be taken to determine how most hard drives are used, in terms of the number of files in each size-type. follow?