Cats shouldn't be teased/provoked.  Probably why he hisses at things
that someone has teased him with.

My cat does the same thing.  He has gotten better in his old age (turns
3 in February) but if someone or something doesn't give him space when
he first meets them, he'll hiss for a week until he calms down.  I was a
little worried when I bought one of those Roomba vacuums that he was
going to have a big problem.  So that he wouldn't freak out every time I
used it, I tried to let him get acclimated to the new thing in the
house.  I left it out of the box in a corner for a week, and by the time
I stared using it, it was old news to him.  He does like to play with it
and his eyes follow it around the room as it picks up all those little
dust bunnies.  My advice is to encourage new people (or things) to let
Tomboy get used to them before they force the issue.

if your boyfriend is provoking your cat then get rid of your boyfriend,
he is obviously a twat and has no respect for other living things and
certainly no respect for you if he is going to torment the thing you
love most ie your pusscat. You have no room in your life for someone
like that so tell him to hit the road and find someone who has more
respect for urban tigers.

bookie

if your boyfriend is provoking your cat then get rid of your boyfriend,
he is obviously a twat and has no respect for other living things and
certainly no respect for you if he is going to torment the thing you
love most ie your pusscat. You have no room in your life for someone
like that so tell him to hit the road and find someone who has more
respect for urban tigers.

bookie