The noun brainchild is used to refer to a product of one’s creative work or thought (the child of one’s brain, of course!). This heady compound is used of events, campaigns, companies, or elaborate projects—or the animating idea behind them. Use of this term usually connotes a degree of admiration for something truly original, and is almost always used in the context of giving credit or attributing success to a certain creative individual. So where there is a brainchild, there is usually a "brain parent" mentioned nearby.
Something that is incessant continues without interruption—and is more often than not a source of irritation! Incessant chatter near your workstation might disrupt your concentration; incessant whining in any circumstance might deplete your patience; and incessant demands, as from a boss or from any other source, might make you feel exhausted or taken for granted (or both!). When not used to describe undesirable situations such as these, you may find incessant used in a more neutral sense to describe continuous and unrelenting rainfall, or other weather events that carry on seemingly to no end.
Something that is stale has lost freshness, such as a stale slice of bread, or has lost novelty or interest, such as a stale joke. That crusty old joke may also be described as hackneyed. Something that is hackneyed is commonplace or trite and worn out by overuse. This term is especially used of words, remarks, or styles of expression that are clichéd to the point of seeming lifeless and uninteresting. So synonym seekers beware: while it may be tempting to slather this adjective on a piece of stale bread, hackneyed simply doesn't make sense as a descriptor for brittle day-old baked goods!