wake up

I made a speaking trumpet of my hands and commenced to whoop “Ahoy!” and “Hello!” at the top of my lungs. […] The Colonel woke up, and, after asking what in brimstone was the matter, opened his mouth and roared “Hi!” and “Hello!” like the bull of Bashan.

Wake your brother up; it's time for school.

Some businesses were slow to wake up to the importance of the Internet.