How to select 5 random on table1 and select random row on table2 joining table1?

I have two tables... My subdomain_table contains almost 10,000 records and my webpage_table has few millions of records... WHat I want to do is to select 5 random subdomain_id then select a random webpage_addr for the randomly selected 5 subdomain_id... My subdomain_id has lots of GAP due to deletion...

subdomain_table ---subdomain_id ---subdomain_name

webpage_table ---webpage_id ---webpage_addr ---subdomain_id

The output woulb be something like this row01 : subdomain0001/webpage85555 row02 : subdomain7008/webpage92344 row03 : subdomain0003/webpage00002 row04 : subdomain0104/webpage10045 row05 : subdomain1005/webpage00601

I'm having so much difficulty getting what I wanted to happen...

Please help me, TIA and best regards...