i must admit that in the years that I worked in D&D funny noises on 121.5 were not a problem. If I was there today with the current systems my response to funny noises etc would be "{callsign} this is {centre} distress and diversion, your position is{lat/Long} what is your emergency?" as they will realize that the callsign was us identifying them so they were no longer anonymous, I would expect them to go quiet.
What is not realized by the morons is that they may think its quiet and a really good time to play silly games but D&D has receivers spread all around the FIR and may be handling a MAYDAY that they cannot hear. But D&D can hear the morons and the emergency aircraft that really needs assistance. I am not sure what legal action for recompense would be taken against a 'making silly noises pilot' who caused the response of D&D to a real emergency to be thwarted, but I am sure the legal representatives of the dead would take some action. Remember that in UK at least morons are not anonymous the autotriangulation is very fast and accurate.
I am not overstating things - I was involved in a rescue where a downed aircraft alert was due to someone hearing intermittent ELT on 121.5 luckily the frequency was not blocked by giggling 'cruise' pilots.