Here's why:
* Tonic is a noun: It usually refers to a substance, like a beverage or medication, that invigorates or restores.
* It can be used metaphorically: Someone might say something is a "tonic for the soul" or "a tonic for the economy," meaning it has a positive, revitalizing effect.
If someone calls you a tonic, it's likely a playful or figurative way of saying you're:
* Uplifting and positive: Like a refreshing drink, your presence makes them feel better.
* Energetic and inspiring: You bring a positive energy and spark their motivation.
* Helpful and restorative: You have a calming and soothing effect on them.
However, without context, it's difficult to say for sure. It's best to ask the person what they mean! They might just be making a quirky, humorous comment.