As a medical professional, a lot of areas won't let you donate blood if you've gotten a tattoo in the last year due to risk of HIV (and other diseases due to an unclean tattooing environment).
It's just a safety precaution.
If you are talking about the USA, it also depends on the state. If the tattoo parlors are not regulated by the state, then yeah, you'll have to wait. If they ARE, then no, they'll let you donate blood. Or at least, that's how it is where I live.
You can. Honestly, those precautions are coming mostly from when tattoos were more of a taboo topic, and people were getting them in shady places. But now? Well, certain states have people in charge into going to those places and making sure everything is in order. Like when a restaurant gets an inspection from the city every now and then to see if they are doing everything correctly, otherwise they'll force them to close. Pretty much similar concept.
There's a football player for my local club called Jonjo Shelvey who has Alopecia, and a young boy with the same disease basically wrote him a letter saying how cool he was and all that, and Jonjo invited him to Swansea, put him and his family up in a good hotel and made them executive guests for a football match, and then made the boy mascot for the game. Moral is, not all football stars are self-absorbed jerks. Some of them are pretty decent guys.
Can't give blood if you get tattoos (recently)
Sex with strangers or interveinous drugs. I do those things and they'll still take blood. Just say you didn't. It's not like they check
This IS true, he has done it several times. Sometimes he doesnt even make it public, and its the family of the child who spreads the word. He also donates a lot and encourages his team mates to visit hospitales. Plus, he once kinda made a kid wake up from a coma, but that story is too long (you should probs google it tho).
It's just a safety precaution.
Sex with strangers or interveinous drugs. I do those things and they'll still take blood. Just say you didn't. It's not like they check