go in (to do something)

You can use the phrase "go in" to talk about approaching something. For example,

Sometimes when you go in to pet her she'll, like, freak out and try to scratch you.

People usually use "go in" in the phrases "go in to ___" or "go in for ___". These phrases explain the reason for approaching. Use "go in for ___" with a noun:

I tried to go in for a closer look, but as I approached it swam away.

Use "go in to ___" with a verb:

The other guy went in to try to punch him, but he grabbed him by the arm and slammed him on the ground.

(someone) comes in (to do something)

Use this phrase to talk about someone approaching you. Usually, the person who's approaching has some purpose. They may want to attack you, to look at you, to hug you, etc.

You can use the phrase "come in for ___":

Don't you hate it when someone you've just met comes in for a hug but you feel like, "Hold on, I barely even know you!"

Or you can say "come in to ___" followed by a verb:

I could see that she was coming in to grab me, so I backed up.

kiss (someone) on the (body part)

To explain which part of a person's body someone kissed, you can use the phrase "kiss ___ on the ___":

He kissed her on the forehead.

Some of the most common places to kiss someone include:

• on the lips
• on the cheek
• on the forehead