Aruki means walking. Sumaho means smart phone. In Japan, people call mobile phone SUMAHO or Smart phone. So, Aruki-sumaho means looking at smart phone while walking.
Sometimes you see the sign, 'Aruki Sumaho Kinshi', which means do not use your mobile phone while walking.
あるき　スマホ　はだめですよ！！

Meccha means very or really. Meccha comes from mecha-kucha ni. Mecha-kucha means awfully, chaiotically. Japanese people often say that mecha-kucha takaine, which means it is very expensive.
Meccha is used among younger people nowadays, instead of mecha-kucha. Originally Meccha is used in Kansai area (around Osaka). Younger people tend to use Kansai dialect to sound more posh.

Usually YABAI is used as a negative meaning. Yabai means that it is not good, or it is dangerous.
However, nowadays, young people often use YABAI as a meaning of very good!
For example, if they taste really delicious sweets, they might say YABAI NE! They mean that
that sweet is really nice! If boys meet very cute girls, they might say YABAI!! They mean that the girls are very cute and pretty!

During Golden week, I went to USJ (Universal Studios Japan!!!), since there was a new attraction called Dispicable Me opened. Minion! Minion! Minion!
There was also a street show of Minions, called Hacha-Mecha minions.
So, what does Hacha-Mecha mean?
Hacha-Mecha means chaotic.
We say that my girl friend is Hacha-Mecha. However, we use Hacha-Mecha in more cute way, rather than serious way.
ミニオンははちゃめちゃだなあ！！！