My hens LOVE the rain! They stay out in all day much to my disapproval... Most of the time I limit them but I have never seen them mad while wet. Now I have seen them mad when I run out of treats when they have a looonnngggg baaaaaaaaaaaaaaaawwwwwkkkkkk baawwwwkkk saying in english GIVE US SOME MORE NOW!!!! LOL
Wait 'til you see them in snow! We had a very snowy winter last year and my flock practically refused to come out even when I'd shoveled the run. One of the hens flew through the human-door into the un-shoveled garden and sunk right in up to her crop. That was one angry hen!
In a downpour they seem to be more irritated than mad. Living in the sticks we often heard this saying when somebodys mom was looking for them with a switch. When moms were really mad they were madder than a wet hornet, although the switch stung whether from a wet hen or hornet.