Moaner.
Negative Nellie/Nora/Norman/any other alliterative name/no name
Melodramatic Mary/May/Mellie/any other alliterative name/no name
Childish
Impatient
Drama Queen
Extremist/add extreme to any of these other words
Faultfinder
Complainer
Bellyacher
Grumbler
Whiner
Malcontent
Grouch...
Right. Now anyone complaining about people who say "Can I get..." are bedwetters, too. As are people who complain about mixed up "there/their/they're". Also, anyone saying "could/should of" instead of "could/should have" are bedwetters too.
Because being annoyed by a phrase, whether on the...