Ads in steam?

[Angelos]

My friend got some random ads in steam XDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDD

 

[MattIs]

You seem to have some kind of Malware.
I recommend you get Antivirus ASAP as you never know what may be on your PC.
I personally use ESET. I recommend using the free version of that or AVG and you should be fine
If that doesn't work download a malware remover (malware toolkit always used to be the best if I remember correct).

 

[Hyperlate]

RIP to your friend XD