Yes you can but it will sting like hell
If you forget to put on deodorant, you can freshen up by washing your underarms with soap and water. You could also apply a bit of baby powder or baking soda to help absorb any odor. If possible, consider keeping a travel-sized deodorant in your bag or car for situations like this.
On your underarm
I think that an average person should put on deodorant at least 1 time a day. I personally put it on 2 times a day.
you did not put on deodorant or you did not put on enough.
You pick out all of your earwax and then put in on paper.
Armpit
I'm gonna go with no...
you would smell, like, super bad
wash your armpits and put deodorant on.
depending on how strong ur odor tends to be
Yes, you can pack spray deodorant in your checked luggage when traveling. Just make sure it complies with the airline's regulations on liquids and aerosols.
ya, probably it will fell good, and make it smell good :)