Here are a few common ways:
* ヘン (hen) - This is a general adjective that means "strange" or "odd." It can be used to describe people, things, or situations.
* キモイ (kimoi) - This is a more informal way to say "weird" or "gross." It is often used to describe things that are considered disgusting or creepy.
* ヤバイ (yabai) - This word can mean a variety of things, including "dangerous," "bad," or "weird." It is often used to describe things that are unexpected or out of the ordinary.
* 不思議 (fushigi) - This word means "strange" or "mysterious." It is often used to describe things that are hard to understand or explain.
If you want to convey a more playful tone, you can use the word ヘンな (henna). This word is similar to ヘン (hen), but it has a more lighthearted feel.
For example, you could say ヘンな人 (henna hito) to describe a person who is a bit eccentric or quirky. Or you could say ヘンなこと (henna koto) to describe a situation that is a bit strange or unusual.
Ultimately, the best way to say "weird" in Japanese depends on the context and the tone you want to convey.