You'd think the story about misposted floppies is apocryphal but the reality is that it's happened on multiple occasions - as has the "coffee cup holder" and even the "I can't use my computer" call which turns out to be a power cut (2 instances in my own support staff for the latter)
I've personally encountered (in a previous life) the oft-related story in the TV industry of toddlers posting toast+jam in the front slot of VCRs (which is less damaging than when they put coins in.). The on-call related part of that is that as trainee electronics tech I got the fun jobs like cleaning printing desktop calculators when someone spilled coffee (with what always seemed like 10 sugars) on them and repairing cash registers from busy pubs that had internals swimming in stale beer when the case was opened. (Thankfully my employer used to charge extra for those dirty jobs and paid extra to those doing them too)
Thankfully these days you can just changeout a keyboard and cash registers tend to be IP67 rated in their electronics parts. Desktop printing calculators are long-gone.