I have a handful of close friends, including my partner, who frequently text me with a completely random picture or video of something cute and/or funny that they found on the internet. For example, a 2-minute video of a pool full of puppies, or an LOL cat meme. I find this very irritating, but for years, my response has been to either ignore it and pretend I was too busy to reply, or I reply with a one-word answer, e.g., "haha", "lol", "cute". Replying (or deciding whether to reply) is always stressful for me because it feels disingenuous, and I always waste a few moments of my life thinking "Maybe I should tell them how I really feel, since they can't seem to figure it out from my lack of enthusiasm or the fact that I have never once reciprocated". But in the end, I usually go with one of my one-word answers because I don't want to hurt anyone's feelings and I don't want them to stop texting me about other things.
I would estimate that this happens on average once per day from each of these friends. Sometimes they skip a day, other times I may get 5 in one day from one friend. Sometimes the pointless intrusion occurs over e-mail or Facebook, but most commonly it is over text. Sometimes the intrusions are more involved than just a picture or short video: it could be a 20-minute video or something I'm supposed to read. I have been present when they get such messages from each other, and it seems like their response is typically a mixture of "AWWW, so cute!" and "Yay my friend saw a random cute/funny thing and thought of me!". So I understand that they want me to feel that way when they send me these things, and I appreciate the intent.
So my question boils down to this:
How do I get my friends and partner to stop texting me random cute/funny pictures/videos/links in a way that ideally won't hurt their feelings too much or cause them to stop reaching out to me in other ways that I like?
At this point, I also need to somehow address the fact that I have been acting like it doesn't bother me for years (and maybe they even think I slightly enjoy it based on my slightly positive responses).