Here are some common idiomatic expressions in English with their meanings and example sentences.

Pale around the gills / green around the gills / blue around the gills

Other expressions that have similar meanings are: pale around the gills, blue around the gills and green around the gills.

When you look green / blue / pale around the gills, you look very ill.

• Are you ill? You look green around the gills.

• I think I should go home and get some rest. I feel a little pale around the gills.

In these expressions, it is possible to replace the around with about.

• When I saw John yesterday, he looked a little green about the gills.

•Ever since eating the fish, I have been feeling a little blue around the gills.

To keep one’s shirt on is to remain calm.

• Tell him to keep his shirt on until dinner is ready.

• I will be ready in five minutes. Keep your shirt on.

The expression keep your pants on has the same meaning.

• You’re next. Keep your pants on.