Okay, I get it. I am 5'1'', bubbly, and energetic; I am pretty damn cute. This does not mean that I am ever okay with being tickled.
For as long as I can remember, including in my childhood, I have hated being tickled. The suckiest part about hating to be tickled is that our natural reaction to tickling is laughter, which makes people believe that the person they are tickling is enjoying it, when in reality we have no say in the matter. This becomes increasingly problematic, especially as more stories of sexual harassment come out in the media; it is so easy to say "but she was smiling and laughing". Someone's body can smile and laugh and that still does not give you permission to touch it.
Some people, especially kids, enjoy being tickled. They like the playfulness of it all, especially when being tickled by parents, peers, or other adults that they trust. The idea of "the tickle monster" is great for the kids who want that kind of attention, but I was never one of those kids. I have always liked to have agency over my own body, and if an adult ever went to tickle me, I would always say "NO!", though this would not stop them. They took my "no" as a "try me" and would tickle me anyway, and I would usually end up sobbing as I laughed hysterically without agency.
This has not changed into my adulthood. Especially people with whom I interact romantically, their instinct is to tickle me even when I resist. These people are not assailants, they are people who in other, more overtly sexual situations would definitely ask permission before touching me, but because we have accepted tickling in our culture, they do not ask. My advice to you, anyone who spends time with me, ask. I will probably say "no", but fuckingask me before doing something to me that makes my body literally spasm. If you do not, I will do anything I can to get you off me, and will most likely bite you in the process.
When you tickle me without asking you are not being cute, you are taking control of my body without my permission. You can't do that. No one can.