Here are the explantions of the idioms I posted last Friday.

And Bob's your uncle! This simply means that a simple solution can fix a problem.

Just restart your computer and Bob's your uncle!

Donkey's years. A very long time since you have done something.

I haven't been on a boat in donkey's years.

To go pear shaped. When a plan goes very wrong.

Our plans host the underwater board game competition went pear shaped!

A fly in the ointment. A drawback/Disadvantage

Ointment is a type of oily substance (like Vaseline) that you rub onto your skin. This is something that was used in ancient times until the present day. Some ointments were quite smelly and could attract flies which could end up stuck in the liquid. The person who prepared the ointment may not have noticed the fly and the person who bought the ointment for their skin might be surprised/disgusted when they rubbed a dead fly on themselves!