If you use half-width katakana all over the internet, you'll end up making people furious sooner or later.
Literal
Half-width katakana [object-を] internet-above [possessive-の] various places [at-で] use-[if-ば], someday frown [object-を] buying-up thing [to-に] become [emphatic-よ].
半角カタカナ ('half-width katakana') is a Japanese computing concept — the legacy narrow-width character set that causes encoding problems and is considered bad netiquette. 顰蹙をかう (ひんしゅくをかう, 'to incur people's frowns/displeasure') is a set phrase using a rare kanji. ~まくる is a suffix meaning 'to do excessively.' いつか ('someday') warns of eventual consequences. A niche but very real piece of Japanese internet culture.