In United States slang in the 1910s and early 1920s a "Jelly bean" or "Jellybean" was a young man who made great efforts to dress very stylishly, presumably to attract women, but had little else to recommend him; similar to the older terms dandy and fop and the slightly later drugstore cowboy. However, the word was also used as a synonym for pimp.
In the semiconductor industry, a "jelly bean" component is one which is widely available, used generically in many applications, and has no very unusual characteristics - as though it might be grabbed out of a jar in handfuls when needed, like jelly beans. For example, the 741 might be considered a jelly bean operational amplifier.
To us, jelly beans mean five quid for a small handful at the flicks and a cavity or three in our mouths. Get you additives on and wear our colorful, sickly-sweet tee!