How do I complete the "tag 5 white ghosts" mission in Doodle Jump?

I just played Doodle Jump for a while and I came across missions (version 3.18 on iOS). One of my missions is called "tag 5 white ghosts". I couldn't figure out how to complete this mission. Any suggestions?

Randomly there will be cherries that appear that turn monsters into white ghosts. It's sort of like Pac Man where you can "eat" the monsters, but you just jump into them and they disappear. That is how you tag the white ghosts. Luckily, you do not have to tag all 5 in the same round as cherries are random and sometimes only pop up in front of one monster.

Hope this helps!